I also think Bittu was harsh and wanted to humilliate Roma because of some previous antecedents... Roma may not be the only one right here. Perhaps Roma had mistreated him in the past..
Trishna was a victim of Roma's immaturity/childishness... I think she was reacting in hot blood to Roma.
Will she keep a grudge against Roma -after all it was an RK's film audition - or will she forgive and forget?
PS - Trishna already had her chance for the audition and she couldn't make optimum use of it.. Why blame Roma?