hi, so

@emmanuelle33333Whoo... that is quite a mess of issues.
I hope I can help some.
First, to solve the issue of the rental properties. (If I understand the problem correctly )
Take all the mods / saves / tray files out to your desktop.
Delete the cache ( thumbcache )
Repair game
Start a fresh game just long enough to create a sim, move them in somewhere and save as a new save. FOR YOUR SANITY make sure the fame opt in is unchecked in the menu game packs options to get things going.
NOW... add your mods back in 50/50 style ( or, just small doses, starting with ones that you know have no affect on lot types ) As long as everything is working as you load them and test by going in game ( including the ability to label as for rental and not for rental lots, your fine )
Now.. add the old trays back and your old saves.
You should be able to load the save ( any save ) and have it working again. If you have a save from an earlier time of the family you specifically want, load it even. All sims and lots will be saved regardless of sim loaded, tho' it could be old.
Once you know they are working, all saves should be good. You can try resave a save in the menu, and see if that helps.
That lag on loading screen often means the most recent save was corrupted. So you should do all the above and try to load a slightly older save, if your still getting massive load times either one of your tray homes is FUBAR, or a mod is.
Definently check your mods for age. Anything younger than December 2023 could be a suspect. ( I have many from before, but most core mods were ruined in December and need an update, most have been updated )