When opening a UFO Glyphs 2.4rc1 ignores unicode values for glyphs that are not in GlyphData.xml. For example U+1D6C LATIN SMALL LETTER B WITH MIDDLE TILDE. The glyph imports fine, but is missing its unicode value. I know I could make a custom additional GlyphData.xml file, but that would be local to my machine.
Glyphs ought to respect the defined unicode value in the UFO even if it’s not listed in the app’s internal data.