What language is this?

Mojibake.

French.

My guess is it's UTF-8 Unicode (any non-Latin language) being interpreted as some standard for 8-bit text. (Windows CP-1252 for example, but not that one because it doesn't have the block made of lines character)

Looks like mojibake to me.

I'm guessing a language that the device doesn't have a proper font for.

I'm guessing someone failed to include a font pack for icons with the release, so what we're seeing is the unicode gibberish that would be styled and replaced with icons from the font pack if it existed, but since it doesn't its getting rendered with a default font instead. It could also be something else entirely, but that's my initial assumption.

yes

Antarctic