I can’t find some glyphs in the pre-built language lists.
For instance, here are some who’s missing UC and LC:
Ebreve, Gcircumflex, Ccircumflex, Hcircumflex, Itilde, Obreve (plus more)
I always made them and they can also be found in many other fonts. Is this a bug or do you guys know something which I don’t?
They are used for romanization of some Indic languages or Esperanto.
Ah. And are they not necessary?
Would not say not necessary but probably very rarely used.
I have done some very extensive (language-agnostic) research on real-world use of characters.
On the basis of this, I am typically including these characters in addition to the ones suggested by Glyphs:
/Gcircumflex/gcircumflex/Hcircumflex/hcircumflex/Jcircumflex/jcircumflex/Scircumflex/ scircumflex/Ubreve/ubreve
In contrast to Glyphs’ suggestions, I am not including these:
/Hbar/IJ/Lacute/Ldot/Eng/Tbar/Tcedilla/hbar/idotaccent/ij/lacute/ldot/eng/tbar/tcedil la
Depends on what you want to do. IJ/ij and Ldot/ldot are deprecated as characters, but not necessarily as glyphs. I recommend including Ldot/ldot because Glyphs can build the Catalan localization with them. You do not need the IJ/ij unless you give it a different shape (which may be the case in cursives). Most of the circumflex letters you mention are needed for Esperanto only.