I do not have a problem with it at all - in fact its so commendable of her to be in the role and deliver her dialogues, and of course of Balaji productions for having her. There have been controversies in world media of discriminating against various things whilst taking on potential artists.
In some areas, the minor roles have a much more definitive method of delivering their role than even Santu. Santu sounds quite bland and apathetic in the most moving of moments sometimes to myself. I guess the role she is portraying requires that, and despite the tears adding to the realism of her situation...it still sometimes feels that she is reciting. Motaben, DM and Pinakin are by far anchoring the show...
Kabhi lagta hai kay saara bhoj show ka unhi kay kandhon par hai. I am a huge fan of the actress portraying Motaben, she does it wonderfully so! The fact that she is hated by so many on this forum (yes, I read the hathya chaar posts!), only goes to show that she has eradicated the distinction of real/fiction...that is what cinema is all about!
Going back to Birwa, its early days and she will be pushed in the right direction I am sure. There needs some tuning in her dialogue and expression but that can only come with experience. A big kudos to the girly though!