This sounds like a good option for the modify plugin you could maybe ask the developer maintaining the modify epub plugin for an option to rename all internal cover files to cover.jpg he might agree to add such an option no harm in asking. And the quality check plugin could add the option to check epubs to see if the overs are named like you want.
Modifiy Epub Thread
https://www.mobileread.com/forums/sh...d.php?t=154371
Quality Check Thread
https://www.mobileread.com/forums/sh...d.php?t=125428