I don't believe there is any way to recover the corrupted saves, unfortunately.
However, with the workaround suggested by
@DrakenSilverwing , it is possible to make further progress and avoid saves corrupting in the first place.
The workaround in question: Avoid using "Save" or "Save and Exit" and never trust an autosave. Occasionally make a manual "Save as" (a new one, don't overwrite the old ones, as overwriting seems to be part of the issue) and clean up saves while you are in the saved game menu.
I personally save before and after any major battle (whether it's against a lord, an army, or taking a castle/city), and keep the last 5 or so saves as backup since my personal crashes almost all seem related to conversations with other lords, ESPECIALLY the after-battle conversations.
