Hyderabad seniors: Builder RERA compliance and legal checks?

Kids moved out last year, so we're selling our big house for a compact 2BHK in Hyderabad, maybe near Gachibowli. Salarpuria Sattva's Sattva Lake Ridge looks good, but I'm worried about legal stuff. RERA registration check kaise karte hain properly? Kya red flags dekhne chahiye? Also, builder ka track record kaise verify karein before signing anything? Agar delay ho jaye, RERA mein kya options milte hain? Is it actually helpful, ya bas paperwork hai? Any experiences?