Thanks very much for the reply. The enhancement that you're thinking about sounds great.
It seems similar to the way the file remaming function presently works, so I'm wondering if we could pass a number in the file name via a storable variable into an id, or if the id generator can have an option to replace numbers in sequence in selected files?
This is how I used the TOC generator to get around the regex limitation in the first place, so it might be easier to let us configure sigil_toc_# in preferences -- to either emulate the behavior found in version 7.0 or 6.2. You have the old code so branching logic may save the time and effort of developing something new.
If, however, you decide to develop a new tool, I have some thought on that too, so please let me know if I can be of service.