I don't think it has anything to do with the source control bug/issue. Haven't had object loss myself and Steam says I have 75 hours in the editor. I get that message constantly.
Far as backups go, these are the folders:
Divinity Original Sin Enhanced Edition\Data\Editor\Mods\YOUR MOD
Divinity Original Sin Enhanced Edition\Data\Mods\YOUR MOD
Divinity Original Sin Enhanced Edition\Data\Public\YOUR MOD
I created a batch file that backs them up in folders with a time stamp, it's super handy.
Here is the script if you wanna use it, just tweak the folder locations to what you need:
ECHO
Format - mmddyyyy_HHMMSS
echo %DATE% %TIME%
echo mm = %date:~4,2%
echo dd = %date:~7,2%
echo yyyy = %date:~10,4%
echo Timestamp = "%date:~4,2%%date:~7,2%%date:~10,4%_%time:~0,2%%time:~3,2%%time:~6,2%"
d:
cd Dunamis EE Mod Notes and Info
cd A Necromancer's Crusade Backups
mkdir "ANecromancerBAK %date:~4,2%%date:~7,2%%date:~10,4%_%time:~0,2%%time:~3,2%%time:~6,2%"
cd "ANecromancerBAK %date:~4,2%%date:~7,2%%date:~10,4%_%time:~0,2%%time:~3,2%%time:~6,2%"
mkdir "editor"
cd editor
xcopy "C:\SteamLibrary\SteamApps\common\Divinity Original Sin Enhanced Edition\Data\Editor\Mods\A_Necromancer's_Crusade_7c57ebf1-6a07-47fc-99e7-8131a2d5ca05" /s/q
cd..
mkdir "mods"
cd mods
xcopy "C:\SteamLibrary\SteamApps\common\Divinity Original Sin Enhanced Edition\Data\Mods\A_Necromancer's_Crusade_7c57ebf1-6a07-47fc-99e7-8131a2d5ca05" /s/q
cd..
mkdir "public"
cd public
xcopy "C:\SteamLibrary\SteamApps\common\Divinity Original Sin Enhanced Edition\Data\Public\A_Necromancer's_Crusade_7c57ebf1-6a07-47fc-99e7-8131a2d5ca05" /s/q
timeout 10
There's probably a more efficient way but that works and it just takes one click. I run it everytime before I start the editor.