Your _localization folder is not actually used, correct? It appears to be a dev version of localization and it confuses the conflict resolver in Irony Mod Manager (also confuses me who is new to modded stellaris). In the real localization folder you appear to have the following problems:

You also have some typos in Localisation_GAPS_Civic_Planters_l_english.yml. Specifically you have spaces where underscores are needed in the identifiers for:
* World_Modifier_GAPS_Vine Vista
* World_Modifier_GAPS_Vine Vista_desc
* World_Modifier_GAPS_Vine Vista_gestalt
* World_Modifier_GAPS_Vine Vista_gestalt_desc
* decision_GAPS_Plant_Vine Vista
* decision_GAPS_Plant_Vine Vista_desc

Localisation_GAPS_Civic_History_Of_Skybattles_l_english.yml has multiple definitions of sm_GAPS_SkyBattler_Hanger and sm_GAPS_SkyBattler_Hanger_desc on lines 7 and 53. If I had to guess, the one on line 7 is deprecated. But there is also a typo on line 54: "isntead" should be "instead".

Also, a similar copy/paste error in common/buildings:
Buildings_GAPS_Undergrounder_City.txt defines building_GAPS_Subterrestrial_City_2 twice. I think the one on line 150 should be building_GAPS_Subterrestrial_City_3 as the one on line 75 upgrades to that but 3 is undefined.