I just work a few days with Glyphs.
I think that it would be more flexible to have the ability to use multiple selectors like *, or ? or @ or [] etc. or any others you like.
for example
if i would like to quickly build custom list to view all letters with ascenders I will be able to quickly filter it using brackets and typing inside [hklmbd], (like in GREP etc.)
or if I would like to see all alternatives of letter l and b I can filter typing for example [l* b*]
Now it is very easy to see every letter with acute, but it is very hard to quickly filter all letter started from for example letter e like: eacute, eogonek etc. Instead of this we have the result of all letters which have in name letter e
Or maybe it would be easy to use such joker like @ to filter classes.
And because of fact that Glyphs is the VISUAL program it would be easier to type cmd-A after and select the result of filtering and drag and drop them to the sidebar. And in this way define new Custom List.
What do you think about it Georg?