well i guess, being new doesnt make my opinion any less valuable than anyone else's opinion.
did it ever came to your mind they are just living a normal life? so what, Ilona doesnt have the highest social skills, but instead is more chatting on her phone or laptop. probably with someone at home? maybe someone important to her so she checks her phone quite often? who knows.
and maybe, just maybe, they know each other from back in the time when they've all been together in motherland russia. Ilona wrote an application to RLC and got into that appartment with Sara and White. She then tried to convice her friends from back home to join her and et voila... it worked. they are now together and work for RLC. Perhaps they've read about the former tenants of that appartment and try to copy them - but we will never know for sure.
I mean, girls their age change their behaviour all the time and they probably dont even know why.