The fitted drain is tortuous in the extreme. Very likely to block in the future. Best to remove it all and start again so fittings at the minimum. What does the waste dive down into? Using solvent weld non 90 deg fittings and rotating waste, could end up virtually straight. Protect the copper pipe properly from potential damage from cement corrosion. I would personally ‘shutter’ around remaining pipes with ply and fill remaining void with fresh concrete. Then bed tray on sand cement mix. Solid as a rock. Pipes still then accessible in future.