SWBF2 doesn't really have a polygon limit like SWBF1. However, these are the advised guidelines for models if ypu're doing something for SWBF1:
QuoteProps - 0 - 500 polys
Buildings - 200 - 3000 polys (the higher end of this spectrum represents large buildings with large interiors)
Vehicles - 1500 - 2000 polys
Characters - 1500 - 2000 polys
SWBF doesn't strictly adhere to these limits though: the stock AT-AT goes over double that suggested vehicular count and I've gotten a 14,000+ poly AT-AT to work in game with limited to no issues. However, player models is another thing: it seems there are tighter restrictions on these as while it won't overload the game to have higher poly models, you will trip the 'low res' threshold if you have a lot pof higher poly units.