I deleted and reinstalled Batman Arkham Knight from epic and when I booted the game, my saves were gone. Is there a way to recover my data?

I did save some of my data a while back to another folder but I'd like to get all of my timed records and progress back. I noticed that in the This PC/Documents/WB Games/Batman Arkham Knight/SteamID/SaveData/Backup folder there is a bunch of save data backup files.

Of note is that I own the game on epic and did not own the game on steam, and yet there are still apparently backup saves in a folder labeled SteamID. However, these files have a date at the end of their file extension (i.e. *.sgm_xx_xx_20xx).

When I get rid of the date extension, the game recognizes the file as save data, but says that it's corrupted and shows 0% game progress. Is there any way to make this data work with the epic version of the game?
Is there any other way to recover save data after deleting and reinstalling the game? Would I be able to access this data if I bought the steam version of the game?

Update:
I bought the game on steam and unfortunately, it didn't recognize the save data in that folder. I tried editing the file extension to make it a .sgm file (rather than a .sgm_xx_xx_20xx) and it still didn't recognize it.

The steam version didn't recognize it at all, which makes me wonder if there's an online check or something that's preventing me from using my own files from the SaveData folder.

Importantly, I converted the most recent of these save data backups and my own manual backup (which works but is outdated) to .txt files to compare them. It looks like the backup files in the SteamID folder is a valid save file, it is very similar in its contents to the old one, with just some changes to some characters and lines.

Due to this and the filesize, I am convinced that this automatic backup is a valid save file and my chance at getting my data back. However, I can't seem to get it to work with either a steam or epic version of the game, and it still has that pesky file extension (.sgm_xx_xx_20xx).

I think this can actually save my data, but I need help figuring out how. How can I get this file to work with the game? Is there any other way to restore lost data?