Pioneer dev forum

I believe it has no İ letter (dotted I). I was testing Turkish translation and that letter does not appear.

Yeah, it doesn't have complete coverage. This is unfortunate.

Its based on the font Orbitron, but we've added a few glyphs to it as we've needed them (thus the different name, its technically a fork and we can't use the original name).

There's probably not much choice but to add any missing glyphs that we need.l I don't know how to do this myself, other than knowing that you need to load it up in a font editor and .. do stuff.

Maybe it can be mapped to existing ones like I or Ì with some code.
http://openfontlibrary.org/en/font/xolonium
this might have a better coverage

I've checked Xolonium. It looks nice and even slightly readable than Orbiteer. But Orbiteer has more character to it and fits the UI better in my opinion.
A quick comparison:
Orbiteer:

Xolonium 22pt:

Xolonium 20pt:

Orbiteer:

Xolonium 22pt:

Xolonium 20pt:

They have a bit different proportions, but that's not really a problem technically.
Xolonium fouls up the layout a bit, but I think that won't be much problem to account for (right?).

I checked, and fontforge seems to work on windows, so I think I can extend Orbiteer with the needed characters. Never really tried, but it seems straightforward, and I can work with vector graphics already. This doesn't include Cyrillic letters, at least not in a reasonable timeframe. Xolonium could be used as a substitute for headings instead of DeJaVu.

Also I realized that some letters, like ő and ű are missing too, which are needed for the hungarian localization.

I'd say we should keep Orbiteer if I can extend it. It's shape and proportions fit in the UI better in my opinion, and there isn't really any readability issue with it either.
It would be useful to collect any missing letter or symbol that is needed (with UTF code too preferably, if known, so I can find them more easily)