Bulk Rename Utility

It sounds like this is possible with BRU, but I'm trying to do it with BRC

Any direction advice?

Maybe come up with a code to translate roman numerals to other sets of characters, perhaps numbers or symbols (as they would be unaffected by Case), then perform your Case, then return you translated number back to roman numerals.

So if
I -> 1
II -> 2
II -> 3
IX -> 9

then do your Case rename

Then
1 -> I
2 -> II
3 -> III
9 -> IX

Now given that you're apt to have numbers in your file names, you might use other characters instead, & so long as you know the translation char to roman...