I'm trying to work through a similar issue with Mamluks recruiting Western European troops after they take over Palestine and Syria from the Crusader States. From what I've come to understand about how troop recruitment works in this mod, each city has a culture assigned to it which cannot change, so even if the Mamluks take Palestine and Syria from the Crusader states, the populations of those areas and the levies they provide are still considered European (even though during the actual crusades the population was almost entirely Arab from what I understand about the period. To which I feel obliged to add the tangent that I understand why the Crusader States should produce Western European levies for game-play mechanics, but I also feel that having recruitment be faction based would provide better game-play mechanics as it offers more consistency of style.)
Anywho, as to clues this could offer you in your search, perhaps try poking around for the city of Venice's culture assignment, not the faction, but the actual city (town) of Venice (New York, New York...) Which files you will have to edit may also depend on whether you're using the lance or native recruitment systems, as I've seen some threads about changing recruitment to match a faction and not a city. It seems like you can edit the values in the levy system to change whether a town/city/fief/whatever recruits from the faction's assigned culture or the city/town/fief/parcelofland's assigned culture.
If the Venetian faction has a cultural assignment of Iberian, then you'd have to edit both that and probably the town of Venice's cultural assignment. If you can edit just the Venetian faction and then change the recruitment system to recruit based on faction culture rather than holding culture, then you would only have to edit the Venetian faction's culture.
I've been poking around in the code myself but I don't have much experience with coding at all other than the occasional small edit.
That said, in this value you provided "p_town_32_1, Repubblica_di_Venezia, fac_kingdom_32" perhaps the value "32" has something to do with Iberian culture, and you could try looking at, say, Pisa, and checking if they have the same value. Again, I have almost no experience with coding, so I might just be spewing complete nonsense.
