/usr/share/xindy/lang/bulgarian/ is in xindy-rules 2.4-1.1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/xindy/lang/bulgarian/cp1251-lang.xdy
/usr/share/xindy/lang/bulgarian/cp1251-test.xdy
/usr/share/xindy/lang/bulgarian/cp1251.xdy
/usr/share/xindy/lang/bulgarian/iso88595-lang.xdy
/usr/share/xindy/lang/bulgarian/iso88595-test.xdy
/usr/share/xindy/lang/bulgarian/iso88595.xdy
/usr/share/xindy/lang/bulgarian/koi8-r-lang.xdy
/usr/share/xindy/lang/bulgarian/koi8-r-test.xdy
/usr/share/xindy/lang/bulgarian/koi8-r.xdy
/usr/share/xindy/lang/bulgarian/utf8-lang.xdy
/usr/share/xindy/lang/bulgarian/utf8-test.xdy
/usr/share/xindy/lang/bulgarian/utf8.xdy