Anyone done anything with these?

Was looking up the OSM process for building Garmin maps yesterday, and came across the concept of TYP files to create custom map styles. (I have dim memories of having come across them many years ago, but I neve delved into it.)

As far as I can tell, there seems to have been little done in this area for the last 10 years or so. There was an online editor which would have been ideal but it’s sunk without trace. There seems to remain the option of a Java-based command line compiler, or two Windows GUIs. I tried “TYPViewer” last night but the map previews don’t appear, so this doesn’t give me much obvious advantage over a text editor. I haven’t yet tried “TYPWiz” because it’s £16 and, while I don’t mind paying, I’d like to be sure it’s worth handing over cash for rather than just manually editing a file.

Any other options? Bonus points for any process that works on Linux.