Builder's hidden legal past: What to check

Been in real estate for years but buying my own flat is a whole different ball game. I'm looking at Prestige Keya Life By The Lake. RERA website pe sirf registration number dekhna enough hai kya? Builder ka past legal track record kaise verify karte hain off the record? Matlab, agar delay hua toh RERA mein kya real options hain? Any advice?