Glyph names change on export

I’m collaborating with a friend on a design project. I use Font Lab Studios and he uses Glyphs. He is doing majority of design work and when he exports the font into otf/ttf some of the glyph names get changed in exported file. It is an Indic (Oriya) font. The base characters have unicode mappings and then there are ligatures/ conjuncts which do not. The names of the former group gets changed i.e from ‘od_a’ to ‘glyph23’. The latter groups keep their name intact. I suppose he uses Glyphs 2.3. Since he hasn’t had the time to post I’m posting on his behalf.

Also can anyone guide how to export OpenType feature file (fea) that Glyphs can read. The file I export from FontLabs has trouble in GPOS. Font Forge export has no classes.

This is the production name conversion. He can use File > Font Info > Other Settings > Use Custom Naming or set up his own glyph data: https://glyphsapp.com/tutorials/roll-your-own-glyph-data

Use Custom naming is already ticked. Also I took a look into GlyphData.xml and it has the necessary names for our character set.
> <glyph unicode="0B05" name="a-oriya" sortName="oy003" category="Letter" script="oriya" production="uni0B05" description="ORIYA LETTER A" />

In project this glyph (uni0B05) is named as ‘od_a’ But this exports named as ‘uni0B05’ (sorry about my previous mention that it’s named as glyph23)

And if you would use the glyph names suggested by Glyphs, you will get proper names for the unencoded Glyphs, too.
If you don’t like to change the names in the .glyphs file, you need to set up your own glyphData file as Mekkablue mentioned.

And exchanging data by OTF/TTF is not the best options. Try the free tool ‘vfb2ufo’. It can preserve much more data, including OpenType feature code.

Thank you Mekka and Georg for the help. I’d prefer to keep the names of glyphs as we’ve named them since we’ve a sizable GSUB and GPOS table and using the glyphs suggested names would mean a lot of name replacing. I was only mentioning that upon export to OTF/TTF somehow the names get screwed up (though it doesn’t while exporting to UFO) and wondering if it’s a known bug.

Thank you for the suggestion on using UFO, I’m not doing much design work rather just OT Tables so it’s ok. Problem with UFO exports is the custom glyph order is lost despite the plist file.