Non Rera apartment

Hello , I am going into an agreement with. Builder to purchase a flat which is approved by Gram panchayat, builder has approval for gram panchayat and layout plan is approved by block development office. In agreement he mentioned that it will take 12 months f om the agreement date for the delivery but did not mention any specific date and mentioned if there is any delay in completing project, they will not be liable for any penalty but has mentioned that 12 % penalty for non payment of funds. Want to ask if it's legal to charge 12% but no mention of pay back for delays. And is it advised to buy property from a builder who has not registered with RERA. Does builder needs to register with RERA even if he has BDO and gram panchayat approval