[DiapDealer]

This is strictly an aesthetic wish, correct? I mean ... once those IDs are created (and are unique), you need not fiddle, adjust--or even look at--them again. I understand wanting simpler, more easily modified code, but this seems to me to be a situation where it just doesn't have any bearing on anything (other than not liking how it looks). The fact is, navpoint ids never need to be adjusted, tweaked, or are even used by any other markup in the ebook. They just need to be unique. They could only be considered "cumbersome" if you actually needed to do anything with them (other than make sure they're there).

If it's that important to you have more aesthetically pleasing navpoint IDs, why not just capture the PlayOrder numeric attribute in a regex search that will allow you to replace the uuid with a simpler, custom ID of your choice based on the incrementing PlayOrder digit(s) you captured?