Better to buy young player with the same price for Cristiano Ronaldo because he has old age and still active and good performance only one or two years later, exactly he has less value right now and not good for future business if Real Madrid really pay high for get back Cristiano Ronaldo, although Madrid not get deal with PSG for getting Mbappe better that fund use to buy young player than Cristiano Ronaldo.
I don't think Perez will bring Ronaldo back to Real Madrid because Real Madrid now need a new and young player to build up the Galaticos 3.0. Ronaldo is not a player for that plan and Perez will not bring Ronaldo back just to use him for 2 or 3 years.
Mbappe is very close to Real Madrid and if Real Madrid succeed with this transfer. He can be the first brick for Galaticos 3.0 and news say Perez want to bring Haaland to Bernabeu next year. With Haaland, Ronaldo is unnecessary so it is best if he won't return to Bernabeu.