If I’m going to have two es ([e] vs [ɛ]), I wonder whether I should also have two ös ([ø] vs [œ]).
And if so, how to represent them.
For the e sounds, I have e vs ä (ε and αι in “Greek”, e and æ in “Croatian”, and е and ӕ in “Serbian”, though I suppose э might also be a candidate).
For ö, I currently only have ö (οι in “Greek”, ø in “Croatian”, and ө in “Serbian”).
If I’m going to separate them, œ seems like the obvious character for the open sound in “Romansh” and “Croatian”, though I could simply go the “underspecified” route. I’m not sure sure about the other orthographies, though an οι–ωι opposition in “Greek” seems like a possibility. “Serbian” is perhaps the most problematic, in part since I don’t know how the sounds are typically represented in languages using the Cyrillic script. Perhaps one of ӧ ӫ ё ұ.