The typeface itself
seems to contain a wide range of characters and thus supports many languages, but the files loaded here with @font
-face as DDG_ProximaNova don't.
This is what it looks like here in Chrome on Windows...
The result is similar on other platforms, it just differs in what font is used to render unavailable characters. For now, it's possible to circumvent this issue by choosing a different font in the settings, but I didn't even know about this option until I've started searching for previous questions before posting.
It also doesn't seem to be very well optimized for screens at smaller sizes, as the dot above lower-case "i" merges with the stem and is hard to distinguish from an "l".