Oh, sorry... in this case it was Vera.ttf from
https://www.archlinux.org/packages/e...am-vera/files/ (md5 785d2fd45984c6548763ae6702d83e20) but it also happened with other fonts I tried
Code:
fbink --clear --truetype regular=vera.ttf $'\nx' # failed to print
fbink --clear --truetype regular=vera.ttf $'x\n' # prints with empty square