Using "Languages" sidebar with custom GlyphData?

I am aware that you can add a custom “Groups.plist” to add new entries and subentries to the “Languages” sidebar, but I was wondering if there is a way to get the “Languages” sidebar to correctly identify glyphs in the font when using a custom GlyphsData.xml?

Yes, you can. See

for an example (done before Buginese was added to Glyphs).

What do you mean by “correctly identify glyphs”?

What I mean is that the glyphOrder sections recognize glyphs as being Devanagari, but in the Languages sidebar there are 0/0 in all categories.

Should those languages not also use the GlyphData? And how can you overwrite the existing languages? All edits I make to the groups.plist will only add new “languages” but not edit existing ones.

The sidebar categories filter by glyph name. So this doesn’t work with your custom names.