compatibility with the province bonanza mod?

That's not possible sadly

I have plenty!
1.Make a distinction between Old Magyar and Hungarian. Old Magyar would be in the Oghur group while Hungarian would be in the South Slavic group. Make the events of the cultural change once the Old Magyar culture is present in Pannonia.
2.Erase the "Basque" culture group and put back the Basque & Aquitan culture into the Iberic group.
3.Put the Gascon & Occitan culture into the Iberic group.
4.Erase the presence of the Aquitan culture in the pre-Charlemagne bookmarks, replace it by only the Basque culture.
5.Erase the presence of the Gascon, Occitan & Catalan culture before the Holy Roman Empire or the Stamford Bridge bookmarks and replace it by the Aquitan culture.
6.Make Aquitan the main culture of Aquitaine present in Charlemagne and The Old Gods bookmarks. And add events that the culture will turn into Gascon, Occitan or Catalan in their regions if Aquitaine is not around anymore.
7.Create Old Italian, Gallo-Latin, Hispano-Roman cultures? They would be present in the rise of the Sassanids (except for Old Italian, which would be present in the Fall of Rome bookmark) until the Charlemagne bookmark.
8.Make events for the Latin, Gallic, Iberian and Celtiberian cultures to evolve into the cultures of the point before.
9.Old Italian will have events of getting fragmented into the Italic cultures (Ligurian, Lombard, Venetian, Tuscan, etc.), Gallo-Latin the same case with the french cultures (Francien, Burgundian, Norman, etc.), and the Hispano-Roman into the ones of the Iberic group (Aquitan, Castilian, Leonese, Aragonese, etc.).

I hope you can implement all of these or at least some of them.

1. Magyar will be in the Finno-Ugric or its own group as they have no connection to slavs in any way.
2. Basque will become Vasconian - Vasconian will develop into Basque over time. Also Basque people aren't related to the French Aquitanians but to the old ancient Aquitanians who spoke a language closely related to Basque.
3. Occitans and Gascons aren't related to the Iberian Cultures - neither linguisticially, culturally or geographicially.
4. Ancient Aquitanians weren't Basque but related to Basque.
5. & 6. Might be implemented if it works with the culture shift events
7. Old Italian won't be implemented ; however Gallo-Roman, Ibero-Roman etc. will be implemented at some point.
8. If the cultures of 7. are implemented then of course there will also be events.
9. Also self explainatory - such events will always be implemented if there is going to be a new culture.

Originally posted by Terran President:

1. Magyar will be in the Finno-Ugric or its own group as they have no connection to slavs in any way.
2. Basque will become Vasconian - Vasconian will develop into Basque over time. Also Basque people aren't related to the French Aquitanians but to the old ancient Aquitanians who spoke a language closely related to Basque.
3. Occitans and Gascons aren't related to the Iberian Cultures - neither linguisticially, culturally or geographicially.
4. Ancient Aquitanians weren't Basque but related to Basque.
5. & 6. Might be implemented if it works with the culture shift events
7. Old Italian won't be implemented ; however Gallo-Roman, Ibero-Roman etc. will be implemented at some point.
8. If the cultures of 7. are implemented then of course there will also be events.
9. Also self explainatory - such events will always be implemented if there is going to be a new culture.

Well, allow me to correct you as someone who knows heavily about history, language and culture:

1.Hungarians (modern ones) have lot of influence from their slavic neighbors, mainly the slovaks, croatians and polish; hungarians ONLY have a finno-ungric language, culturally they're not at all similar to their language-related cousins, they've more in common with thier modern geographical neighbors.
2.The old "Aquitans" were a distinction made by the romans, linguistic and archeological evidence says there was no distinction between the vascones (proto-basques) who lived in the south of the pyrenees and the "aquitans" who lived in the northen pyrenees.
3.In this point you ♥♥♥♥♥♥♥ ♥♥♥♥♥♥♥ it up. Occitans & Gascons are actually iberic by definition (only a pro-french ♥♥♥♥♥♥♥♥ would dare to say occitans are "franco-romance"), their language is part of the ibero-romance languages and they share the same sub-group of languages (occitano-romance) with the catalan and aragonese. To make you understand the close border between these three languages, the catalan language is actually an former dialect of old occitan that became its own language and the aragonese borrows heavily from the occitan language, from grammar to lexicon. In terms of culture, is almost as close, I would dare to say that the difference between catalans, aragonese and occitans (I include gascons inside "occitans") would be as similar as the cultural differences between the russian, ukranian and belarussian cultures.
4.See point 2.
5.Oh, another suggestion to add: Add the "Ruthenian" culture, it would spawn around the XIII-XIV centuries until the early XVIII where it would fragment in between "ukranian" and "belarussian" (this is based upon the historical evidence of how they called the language and people as a whole regionally).
6.Well, I'm glad some of my suggestions were already thought of and will be implemented. Is a shame that old italian would not be implemented.

and if you tell me "b-but in wikipedia says the occitano-romance languages are gallo-romance", that's because they're a transitional language group (and most linguists add it into the ibero-romance language group, that's why I tell ya), like the gallo-italic languages or the central german languages. I don't want to sound rude, but is just to correct ya bro.

1. The problem with Magyars is that they are not slavic - they still speak their own language, identify themselves as Hungarians and not Slavic and overall don't fit into the South Slavic group. Not even in a gameplay perspective. So it will either be Finno-Ugric for historical reasons or its own.
2. Having an entire culture group for only one culture seems kinda unnecessary - and since Roman sources say that the Aquitanians existed it's not too far fetched to think that the Vasconians and Aquitanians were closely related peoples of the same culture; like bavarians and austrians for example. If you give me a few sources to prove that they were 100% identical and spoke the same dialect and had the exact same culture it will probably replaces. But since the Pyrenees divides both more or less it's not too strange if both developed their own cultures - especially since according to Caeser the Aquitanians were primarily sailors. But again due to the fact that the entire region was inhabited by different tribes it can become confusing as each tribe has its own culture, sometimes even language and history.
3. I never said they were Franco-Romance - but the Occitans are like the French romanised gauls - but due to their geographical location they were more heavily romanised unlike the gauls in the north who were conquered by the Franks early on. I would give them their own culture group since they aren't Iberian in the sense of speaking a common language and having a common culture specificially. Neither are they French - Aragonese is closer related to Castillian and Leonese while Galician is closer related to Portugese. - But again: I have to keep the gameplay in mind and adding too many culture groups and events could seriously ♥♥♥♥ it over - I would have to add events that the gauls are romanised over time - then I have to add events that they develop differently from the northern gauls which can only be done by either making events for each region or by making events for specific nations - but when having specific nations there is no guarantee for events to actually take place. And by following regions it might be weird if there is suddenly a French culture despite the Frankish tribe being conquered by the Cheruski in 340 - ET is unpredictable in that part. Still have to look about the bookmarks etc. tho
5. I wanted to add Rus and Ruthenian as culture with Ruthenian later splitting into Byelorussian and Ukrainian and Rus developing into Novgorodian and Russian - actually I also added a new Slavic culture group which will split into East, West, and South Slavic after the foundation of certain countries like Poland or if a certain year is reached.
6. Old Italian would be too abstract and difficult to implement - a culture to change, then unifiy, then split again but only when country xy and vw conqured province z ... eh ye.

I'm not working on this mod alone and have to keep certain regions, event and gameplay perspectives in mind. So ye

Well, it triggers me a lot about the occitan case because I deeply know about the culture and history of the region and they're often heavily represented just like "french but they speak slightly funny", like I said before, they're more like iberic than frankic because of cultural and historical reasons, but also depends heavily on the region, as Occitania is rather a union of historical nations rather than a big region of its own: regions like Languedoc (Toulouse, Rouergue, Septimania, Foix), Gevaudan and Provence are more related ot their iberic brothers (mainly the catalans), while the region of Gascony has deep roots and relations with their basque neighbors (I mean, the name of "Gascony" is just a term derived of "Vasconia"), while the peoples of Dauphiné, Auvergne, Limousin, Poitou and Bourbon are kinda their own thing.

About the Magyars, is kinda the same thing as before and kinda a bit more from experience (if my croato-hungarian gf told me was right), indeed, the magyars are their own thing, but their culture is not alien to their slavic neighbors, the hungarians have shapped themselves to their surroundings, with around 20% of most words in hungarian being of slavic origin (mainly west slavic and south slavic borrowed from languages as Old Moravian/Slovak, Polish and Serbo-Croatian), geographical names & toponyms (Balaton, Sopron, Vas, Pest, Szepesség, Esztergom, Csesztve, etc.), culture (pieces of traditional clothing, gastronomy, music, tranditional dnaces, etc.). The Hungarian culture being inside the south-slavic group wouldn't be that off, to not say making hungarian an alien culture to that group would be kinda worst to a certain point.

Well, with "french romanized gauls" is a wrong way to describe the occitans. Aquitania (all that was Southern France) used to be ruled by the Visigoths by the V century and then it was conquered by the Franks in the early VI century, despite that, the visigothic culture remained in the region and the former nobles of the region remained ruling, many important noble houses of the region are of visigothic origin (houses like the houses of Barcelona, Toulouse, Montpellier, Foix, Béarn, Urgell, Maison de Gascogne, d'Empúries, etc are of visigothic origin), the franconization of the region I would say didn't start around the XII and XIII centuries, with the rise of houses like the Lusignan, the rule of the angevins in Aquitaine, the fall of the house of Toulouse after the cathar crusade and the loss of the catalan-controlled Provence to the Valois-Anjou.