I never needed apostilles on my birth certificate when applying for residency permits. However, I did need sworn translations of it, plural because the translations couldn't be from more than 90 days earlier than the application, each and every time, apparently they were concerned that my birth certificate might have changed since I was born and they couldn't just accept the translation from my previous application a couple of years earlier.
If she want to stay in Poland more than 3 months she can get permission to live in RP because she's wife of polish citizen ( art. 53. 1, 1) - act of foreigners ) for two years.
The really important thing to note is that she must submit her application for the two-year permit no later than 45 days before the end of her 90-day visa. If she gets it in before that deadline, she can stay until a final decision is issued, no matter how long that takes; if she doesn't and the two-year permit isn't ready when her 90-day visa expires, she has to leave Poland (and the entire Schengen zone).