thanks a lot for bringing this up. So far nobody else has reported the problem of not being able to see parts of the pdfs due to not having the fonts installed. So for the moment I think it is ok the way it is.
In case other people encounter the same problem (if anyone does or did, please post here) then we might need to include a download link.
We use Google fonts, which are free license and very widely used, so usually most peoples devices can read them