iMac late 2012 back to Ventura

Hi all, I am running on OPLC 1.3, but I’m stuck since Sonoma 14.3.1. It does not start anymore, staying at the third of the startup bar.

I can’t make a fresh install of 14.3.1, it won’t start, same issue.

14.3 was working, even if regularly freezing, and was slower compared to Ventura.

So now I’m back to Ventura, with the gain that it doesn’t freeze and it’s slightly more reactive.

But as my last backup is with Sonoma I can’t restore my data from Time Machine without putting Sonoma again.

Do you have any advice, more than a copy paste of the data from the backup, to make a better downgrade?

Or any other advice? Thank you.