Of that 6,000, I can tell you wholeheartedly that there are no more than 35% of those actually working on the game at most.

Rockstar New York is its headquarters. That's where all the lolsuits come from.

Rockstar Lincoln just does localization, and they'll be defunct in <5 years once AI takes over that field. Not needed.

Rockstar Toronto did The Warriors and a few PC ports (likely none after 2010), probably including the shitty '05 San Andreas port where they broke half the game. Not needed.

Rockstar New England only ever made the Scholarship Edition of Bully. They're not needed.

Rockstar India's entry on Wikipedia's table is literally blank. I have no idea what the fuck these jeets do other than some of the vehicle models in V's post-2018 DLCs.

Rockstar Dundee also aren't needed, there's nothing on them either.

The only relevant divisions are North (Edinburgh) since they're the ones in charge of it all, San Diego, since they probably deal with the driving aspects of the game (they used to make Midnight Club a long time ago), Leeds, since they made a lot of the B-Team GTA titles like the Stories and Chinatown Wars (I think they did Advance too) and London, who worked on Midnight Club L.A. and Max Payne 3.