Tiny question, but does Glyphs support kern group inheritance?
ex.
You have a group set for ‘e’ which is o ← e → e for example. In another character, you set the left kerning group to e, is there way to resolve this so that this new character’s left kerning group is the left kerning group of e → which is o?
Thanks 
You mean sort of like metrics keys/references, but for kerning groups? This is not implemented in Glyphs, no.
I don’t understand why you would want that? What other glyph would that be, for example?
The Set Kerning Groups script in the mekkablue scripts does this for composites.
My process (maybe inefficient) is going through the glyphs (especially non latin characters in greek and cy sets) and set the kerning groups by eye (since the default assigned ones are sometimes set to things like theta ← theta → theta instead of just O ← theta → O) so I manually go over those ones and go like what does this look like kinda thing.
In that case I might set the left bearing to e at that time, but realistically the e glyph is assigned to the o left group, so the glyph I set to e on the left is referencing e which is nothing, since e is itself referencing o.
Its a bit of an edge case, and not really an issue, just annoying when I realize it long after that the kerning group is wrong kinda thing
More details in the Kerning tutorial.
Kerning groups work quite differently than metrics keys. For convenience, one usually uses the base glyph as group key, but you can use any string that makes sense (e.g. ‘lower_round’). All glyphs that have the same kerning group key, are collected into one kerning group.