So for example, by default, to have a glyph with unicode 00DF I need to write down germandbls to "add Glyphs". But I'm looking for possibility of making my own naming-standard, where , for example if I'll write down germandoubles in add Glyphs, it will automatically assign 00DF unicode.

Advantage:
If I could define the path (in preferences) to the file that contains pairs name-to-unicode, I could easily manage my naming system for non-latin scripts.

(I hope it is clear, somehow it is hard for me to explain it in an easy way)

Of course, I could write down my own extension for it, but before I do that, I would like to know if it is possible to set it in RF.

the Add Glyphs sheet allows you to set custom unicodes when adding a new glyph. for example:

germandoubles|00DF

I find it more practical to set unicodes using a script, so each project can have its own custom mappings. something like this:

def autoUnicodes(glyph, customUnicodes={}):
    if glyph.name in customUnicodes:
        glyph.unicodes = [customUnicodes[glyph.name]]
    else:
        glyph.autoUnicodes()

customUni = {'germandoubles' : '00DF'}
        
g = CurrentGlyph()
autoUnicodes(g)

there are probably other ways to do it…

hope this helps!

you can create your own custom GNFUL list…

# GNFUL
germandoubles 00DF

…and then add it in Preferences > Character Set, so it will be used for all fonts:

these custom unicodes are also picked up by glyph.autoUnicodes(), which is quite nice.

(thanks @frederik for clarifying it via chat :)

Generate your GNFUL list with a glyphNameFormatter generator: see https://github.com/LettError/glyphNameFormatter (embedded in RoboFont)

good luck!