So, colonisation actually got quite a bit of work recently in the early stages of 3.8

1) The human has a definitive advantage into knowing how history plays out; no human player would ever willingly give up Azores or Canaries unless they absolutely had to whereas AI will hand them over for peanuts because they are low development and pose no particular significance. The Iberians get the tech advantage to prevent humans exploiting the AI to murder their colonial ambitions with one minor war.

2) All nations play by the same colonial rules; AI doesn't get any bonuses to it. The AI does understand, however, best practices like building the first colony somewhere that has a natural harbour or estuary to take advantage of the settler growth bonus and to colonise regions that line up with it's chosen native policy (or attitude towards natives if you don't have Cossacks DLC and choose via event).

3/4) Any more colonists and the Iberians will colonise the world; the large colonial nation modifier keeps Spain from taking everything with her colonists before anyone else can come along and serves as an offset to the gains from colonialism; large colonial nation gives a merchant but costs a colonist. In vanilla it is conceivable to shut out all other nations from colonisation if you play your cards right; impossible in this case. Your colonial nation will also continue colonising that region for you as they pick up a colonist from their traditions (which you benefit from before they become a large colonial nation and take your colonist).

Thanks for your reply, now I understand what's the thought behind those settings.
But I still think it is way unbalanced to any human player who wants to play the colonisation game beyond playing Spain or Portugal.
The mistake you are making, it's assuming that all players want to play big Nations like France, England or Spain. If you use this mindset then it make sense to balance it this way, but many play Mods like yours for a challenge. If I wanted to play the big Nations and steamroll everything in my path, I would play vanilla.
I will try to be constructive.

1) That's a fair point, though the only way to get the Azores and Canaries is to actually beat either Spain or Portugal which is hard at the beginning of the game (they are allied), unless you are either England or France and get to ally Austria. And even if you manage to win, with the Area of Influence Core system you implemented, I am not sure you can Core those 2 provinces since they are too far away from any other nation, apart from Morocco.
It takes ages in order to be able to Core distant provinces from your Capital, I am not sure it would be any use to annex either Azores or Canaries, though I didn't test it, but considering how long it's taking me to Core provinces much closer to my Capital which I annexed almost at the beginning of the game, I am pretty sure you can't Core those two provinces.
By the way I have a backlog of around 40 provinces waiting to be Cored, just to point out how slow is to Core provinces in Veritas.

2)Again. Fair point. Problem is that by the time the human player gets to the new Continent, Portugal and Spain took already the best spots (AKA natural harbours). Another reason to avoid giving them advantages.
I want to point out again that by the time I got to Americas, Portugal and Spain already fully colonised 75% of the Continent. Only parts of North America was still available, and neither England or France were there yet, so it's not only a player problem, even traditional AI Colonial Nations get stuffed.

3) That's why giving them 4 level advantage sucks (pardon my French).
By the time I catch up with them, they already have 2 colonists and took already all the Harbours.
As a result, in my game, 75% of the Terra Incognita is owned by Portugal and Spain, 20% is still free and 5% is owned by me (Genoa) and France. This never happened in any of my vanilla games.
Don't you think it's a bit unbalanced?

The solution for the early war exploit would be to make the Azores and Canaries unclaimable by distant Nations (because you can't make it a core), that would be the only advantage Spain and Portugal will get.Only if you own their Capital you will be able to claim their islands, you also need to own an adjacent province in order to claim the Capital, so picking the Capital once you win the first war won't work.
It seems fair to me. So instead of an early quick war, you will need several longer and bloody wars if you want to get to the Americas first.
Make the Exploration ideas available at the same level for every one, the Iberian Nations included. You need to rearrange the colonisation range too, so it won't take too long for players to get in range of the Caribbean, since now they cannot easily claim the Azores or the Canaries.
Also add more Colonists, considering that owning an independent colonial nation takes one colonist (why?), and not owning Harbours seriously slows your progress (it's seriously slow).
This way, you still get Spain and Portugal to get to the Americas first but they won't have the huge advantage they have now.
Problem solved.

By the way, why owning a fully fledged colony takes one of my colonists?
It also doesn't seem to apply to the AI players.
Spain owns 5 independent colonial Nations, and since they can have max 3 colonists, by the time a third Nation forms, they should have 0 colonists left, so how do they manage to colonise the other 2 Nations?
Just fix the (early war) exploit, instead of reworking the whole colonisation game which clearly doesn't work if you play a smaller Nation.
My 2 cents.

Gonna have to agree. The dev explanations aren't really satisfactory.

The Iberians getting access to exploration earlier is, in current VeF, probably anachronistic. Originally we gave them much earlier access to allow the historical explorations down the African coast, but all that did was get the new world colonised in 1450 so it was eventually scrapped in favour of events to handle Canaries/Azores/Arguin/etc.
So I can agree they don't need/shouldn't have the jump start anymore, however I don't know how much meaningful effect moving everyone to tech 26 will have for anyone outside of British Isles and France as distance will probably lock them out of reaching anything until the big range bonus at diplomatic tech 31; though in the interim time between 26 and 31 they could at least have worked through some of the ideas to have the bonuses ready once they get the range benefit.

Only the "large colonial nation" colonies take a colonist, so when you're counting Spain's colonies note that Cuba doesn't take one (it's not possible for it to reach ten provinces) and holdings that don't actually form colonial nations (Hispanola) don't cost anything. Spain also has additional colonists from her national ideas.

I definitely don't assume that everyone plays large nations; part of the reason large colonial nations take a colonist away is that prior to doing so Spain and Portugal would colonise nearly 100% of the new world before any other AI got involved. A human playing England or France will jump on exploration as soon as available, whereas the AI takes it at a time more in line with the historical outcome (where England and France were relatively late to the game) which is why you were able as a non-traditional coloniser to get your hands on the USA without more trouble.

We've tried to strike a balance between achievability of historical outcomes, flexibility of options for players, and a reasonable conception of realistic limitation on what could hypothetically be achieved.

Good that you reply, interesting to see your point of view. However, there's also colonization outside of Europe. For example Indonesia.