It's possible that your game files and save location is not where you think it is? Are you looking in Documents? Or OneDrive/Documents?
I disabled OneDrive on my computer because it can cause issues with games. I assumed this meant that it would use the regular Documents folder.
I was trying to do what you are doing, replace a neighborhood, and when I'd go back into the game it would still be the one I was trying to replace. I was baffled because the folders were all there in Documents, and I knew I was doing it the right way. Finally I noticed that the cache files in Documents were not re-created when I started up the game. In searching for the cache files, I discovered that the game was still using the OneDrive/Documents folder. I tried to fix it, so the game would use the regular Documents folder. But it refuses and in the end I gave up. One Drive isn't doing anything, but the game is still using that folder. I'm not sure why it generated folders in Documents in the first place since it ignores that folder.
Edited to add: As for the MeetMeToTheRiver suggestion, I agree those are great. I'd also recommend you look on Mod the Sims at Croconaw's "fixes" for several of MeetMe's neighborhoods. They went back in and tweaked a few things that, for me, made them even better.
