I never tried NGL Biathlon natively because I have no Windows computer, but I get more than 60 FPS with Wine.
What I did was just run the Windows executable file with Wine, close the game since fonts were invisible, run winetricks mscorefonts in the same Wine wineprefix (check the internet if you are unfamiliar with wineprefix, basically it’s the folder of the Wine Windows folder I used to run the game), and then relaunch the game.