Mangold has made comments to the effect that the existing scripts he looked at felt a little too safe and familiar for him, without a firm sense of identity. (To be fair, it doesn't even sound like the material was considered camera-ready yet.) I obviously can't judge a script I haven't read, but that's pretty in-line with what I'd expect the Spielberg/Koepp INDY 5 to be like. It sounds like Mangold and his writers started totally from the blank page, with the only residue from the earlier concept(s) being the involvement of Indy's goddaughter (who I wouldn't assume had the same function or personality as Helena in the produced version) and the idea of a prologue with a de-aged Indy.
China could have been a cool setting, though. It's interesting that the story would have gone to Buenos Aires as well -- you'd think after an installment largely set in South America, they would have avoided that region to mix things up, but had they shot on location (and it sounds like might have been the plan, with Portugal being the stand-in) it could have been justified. DIAL was supposed to have a segment in India before pivoting to Morocco due to COVID levels -- had that worked out, it probably wouldn't have felt redundant to TEMPLE OF DOOM since an urban center would have been visually totally different from the second movie's settings.
Anyway, the main reason I bumped the thread is that the movie arrived on disc earlier this month. Glad it made the cut before Disney inevitably abandons physical media.