/usr/share/tuxpaint/fonts/locale/gu.ttf is in tuxpaint-data 1:0.9.22-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/tuxpaint/fonts/locale/../../../fonts/truetype/lohit-gujarati/Lohit-Gujarati.ttf