I got bunch of back-up wallet files all with random chars names. Kinda hard to guess what is what.
Is it ok if we change the names (to something explanatory). Would be able to import them fine later?
Yup totally fine. Armory doesn't use the filenames. It simply checks that the contents look like a wallet file. On that note, any files you add to the Armory home dir will automatically be loaded by Armory, regardless of their filename.