Some scripts (sample screenshots: Hindi) are correctly shown in the editor (main lyrics, but not in the on-note lyrics):

However, they are not correctly displayed in the singscreen:

So in principle, these scripts are supported by the fonts shipping with USDX, but somehow they are not correctly displayed everywhere.
Not directly related, but maybe it is worthwhile investigating if USDX could switch to Google Noto to avoid "tofu" with "one font to rule the them all" - all languages, all scripts.
@bohning sounds like a good idea and the noto license also looks good. As usual, try and go ahead if you want to ;-)
@basisbit: I already did, check this out. Still has some minor issues, but seems to work quite well so far, both in the SingScreen

and in the editor:

@bohning do you consider the no more tofu branch to be ready to merge? (if yes, please create a pull request) Although I like tofu...
I just created a pull request and am looking forward to your remarks. It currently includes basically all fonts that are available in the previously used fonts, so some of most of them can maybe removed or be provided as a separate language pack (especially CJK because of the size).
And yes, I do like tofu as well (as a vegan), but not in UltraStar ;-)
See PR #386.