Tiberiumkyle

Pausing is meant to turn off most of the UI and prevent you from interacting with the world.

What did you do to try to get the UI to work while paused?

My guess atm is that something is restricting how much memory java actually gets to use, despite it being allocated plenty for the game to use.

Mind including the top bits of the log as well? with 32gb of mem you shouldn't be getting an OOM crash like that unless something is messing with how much can be assigned to java when it's launched.

You really only need to rename the highest numbered save, the rest are backups. After renaming you need to switch the world map to the chosen difficulty, each difficulty keeps separate saves. Once done with sandbox mode tweaks, you can exit out, rename the new sandbox save, and go back to your original difficulty.

If you really must have more than the 300 slots that is the current cap, best bet is actually to shift save to sandbox mode and give yourself extra village centers, otherwise you'd have to decompile some game code, tweak it, and recompile it.

All save data is in game install location, profiles folder. Region saves will be further down, profiles\profile0\saves\worldMap\WorldMaps. Profile0 if you used the top profile slot. You can switch a save difficulty by renaming the zip file to the desired difficulty. Making a backup is recommended in case you manage to break something, fairly easy to do when mucking with the saves, or doing stuff with sandbox mode.