/usr/share/tuxpaint/fonts/locale/gu.ttf is in tuxpaint-data 1:0.9.21-1.1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/tuxpaint/fonts/locale/../../../fonts/truetype/ttf-gujarati-fonts/lohit_gu.ttf