My own Ghaziabad purchase feels totally different

Been in this business for years, but buying my own Ghaziabad place feels different. I'm eyeing Ishaan Group's AU The Sunflower Phase 1. How do you *really* check RERA registration beyond the basic number for projects like this? What specific red flags should I look for in their legal track record? Any title verification steps people often miss, especially around Siddhartha Vihar? Does RERA actually help with delayed OCs here?