A UFO that is exported with Glyphs is not including magical automatic bracket layers magic
There is no meaningful place to put them. At least I don’t see any.
I would expect them in the parent layer. Other libraries solve it this way, for a dollar with bracket layers they create a new glyph in the parent layer called f.e. dollar.bracket.30.
It’s quite hard or even impossible with current tools to automate our process or export our variable fonts. One library for converting glyphs to ufo doesn’t handle this and the other doesn’t handle that.
I still think that being able to write designspace file and all its ufos would be very useful.
even exporting them as individual ufos would be nice, so we can handle the merging as we wish
I said “meaningful”. Just exporting all layers (and there are more than only bracket layers: brace, color, backup …) could be done but would mostly swap the .ufo. Because without their metadata, no other tools will be able to use them. And I’m not sure what ufo editing apps would do with a font that has a couple hundred layers.
You can use glyphLib to generate .designspace + .ufos files.
If using GlyphsLib, then these auto smart corners are not dumped