Hello and welcome to the forum
The autosave function and the resulting autosave file are not intended for your use. It’s intended for use by krita to recover data after a crash.
If you close/quit normally then any autosave file is deleted, because it’s assumed that it’s no longer needed.
You can find more details of all this (it’s quite complicated and comprehensive) here:
The backup file is Altha.kra~ and it should contain the state of your image as it was the previous time you Saved it with Cmd+S.
I suspect that Altha.kra.uTWFAQ is some kind of intermediate file that was involved and the crash has left it hanging around. The advice of a developer would be needed for that one.
I suggest that you rename the files as follows:
Altha.kra → Altha-broken.kra
Altha.kra.uTWFAQ → Altha-what.kra
Altha.kra~ → Altha-backup.kra
Then try opening Altha-backup.kra and see if it has a recent and useful state of work inside it.
Also look in Altha-what.kra to see if it’s even more useful than Altha-backup.kra.
Recently, there was a reported problem with the Save action not working properly if an autosave was being carried out at the same time. I’m not sure what’s happening with that and someone else may know more about it.