In all fairness the prequels only caused minor issues with the EU which a few retrocons dealt with easily.
Jedi aren't supposed to marry but some had kids? They either did so secretly like Anakin did or were parts of rogue Jedi groups that ignored the current rules of the main order.
Someone who was on the side of the Republic during the Clone Wars remembers fighting clones despite the republic army using clones? The CIS tried to form their own Clone Army and he fought that one.
Mon Calamari showing u when the EU said that their first contact with the Galaxy was during the Galactic Empire's reign? That was actually Imperial propoganda trying to rewrite history and they ad really been part of the Republic for thousands of years pre-Empire.
Someone remembers being in the Republic Navy pre-Military creation act? They were actually part of the Judical forces which were the closest thing the Republic had to a unified military pre-act, or perhaps one of the planetary or sector defense forces that existed pre-Act (And honestly the whole no Republic Military pre-Clone Wars idea was IMO utterly insane.
It was only when the second Clone Wars series came out that things became irreconcilable.