Jerm,
I'm using SE 6.1.0.4, and have a few old synths that aren't in your shipped program names files (Roland SC-50 and MKS-100, Yamaha TX802 and TX1P). For simplicity, consider the SC-50 (original sound canvas):
I tried the "new" button in the program names dialog of the setup menu, selected the sound canvas, typed in a list of patches, clicked ok. Nothing happened. When I select the sound canvas (or an instrument including it) for a track, neither the tracks window nor the dialog for setting channels and programs shows instrument names. (By the way, it looks like that dialog box which you get by clicking on the instrument name of a [non-layered] mixer instrument never has anything but numbers. Why doesn't it show the names??)
Is the customization of program names completely dead in this release, or am I missing something? (Probably the latter!)
I also tried cutting down the "Roland SC-88-pro.ins" file (name may not be quite right...I don't have it here to check) as SC-50.ins, saving that in the Metro6 program names subfolder, selecting the sound canvas port in the program names dialog of the setup menu, selecting the SC-50.ins file, ok'ing it. Still nothing.