My Delhi flat's legal due diligence nightmare

Two years ago I saw DPB Buildwell launch Jay Hind Apartment and the legal due diligence was a nightmare. How do you guys *really* check RERA compliance beyond just the number? I'm talking about verifying the builder's track record and title clarity, especially for older societies in areas like Dwarka. Is RERA actually effective for complaints or just a formality, from your experience?