How do you actually check RERA and legal history for Noida Ext builders?

My loan's approved for a 3BHK in Noida Extension, aiming for something around ₹90L, maybe Sector 137 or near Yamuna Expressway. I work in real estate, but buying for myself is a totally different ballgame, yaar. Builders always have some catch. I'm super paranoid about RERA compliance and their legal track record. For example, looking at Msx Developers, how do you guys *really* verify RERA registration beyond just the number? Are there specific red flags in their legal history that aren't obvious? And what about those tricky clauses in the builder-buyer agreement? I know what they hide, but what are the common ones to watch out for in Noida Extension projects like APS Royal Homes? Don't want to get stuck with hidden charges or crazy delays. Any experiences?