5U is in VINs for a 2018 one (so last generation): https://www.vindecoderz.com/EN/check-lookup/9BWKB45U7JP059468
and this part site also uses 5X, 5W and 5U: https://m.oemvwshop.com/5u-2009-2011-c3339/ but not sure if indicated years are relevant.
Also Gx for different generations seems to be widely used instead of just the numbering.

Speaking of Brazilian VW derivates, shouldn’t these have Typ 32B as chassis code like the Passat/Santana instead of B2, which is the (Passat/Santana) generation? https://imcdb.org/vehicle_1915369-Ford-Versailles-B2-1992.html

BX is the platform rather than the model code (Typ).
AB9 is the project name rather than the "Typ" it seems.
Same for NF (cf the English language Wikipedia page)

German Wikipedia is on the side of spanish Wikipedia (or it's the opposite):

- first generation = Type BX

- secons generation = Typ AB9

- third generation = Type NF

https://de.wikipedia.org/wiki/VW_Gol

Currently on the site they are all listed with "Typ AB9" as chassis code, and generation (mk) number go up to 7 (VII) for some models, but not all, I assume a mix between the generation and the restyling: the restyled 2nd generation were named G3 and G4, the 3rd generation was G5 and then G6 and G7 when restyled.
According Wikpiedia there are only three generations, with restylings:
https://en.wikipedia.org/wiki/Volkswagen_Gol
https://pt.wikipedia.org/wiki/Volkswagen_Gol
AB9 seems the code name of the 2nd generation project.
First one would be Typ 30
Second one is listed as Typ 37/5X/5W, I'm not sure to what they correspond. Maybe the facelifts, so 5X = Gol G3 and 5W = Gol G4?
Third (current) one would be Typ 5U
Maybe we could use the mk field for G1 to G7 (having it displayed as G+number then).
So I'm waiting for some input before starting to clean these