Custom chord font XML files - How to edit them?

I started going down the rabbit hole trying to find out how to make fonts that otherwise wouldn't work as custom chord fonts, to be implemented using the XML chord "wrapper" of sorts. I found a forum posts which had a comment far down in the thread with an XML file that works for the font JazzCord. It's a font I've seen Finale and Sibelius users been using since forever (which unfortunately MuseJazz does not reproduce), and the XML seems to work great. Except that for a few things, it doesn't. All m7b5 chords have the b non-offset (should be offset like the 7 and the 5) and gets overlapped by the 7. Also, all dots ( . ) becomes space. Which can be great as a separator, but makes the no chord N.C. look like N C .

I know that you can edit the XML file to fix these, but I just don't understand the documentation on how it's supposed to be done. Additionally, I've been made aware that the file I'm using is kind of outdated, and there are other more up-to-date ways to edit this, though I haven't found any. I'm very happy with the look except the overlapping non-offset b, so obviously I'm not going to put huge effort into these small changes, but if anyone has done this and could walk me through how to easily fix it, I would be very grateful :)