/usr/share/xindy/lang/greek/ is in xindy-rules 2.4-1.1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/xindy/lang/greek/iso88597-lang.xdy
/usr/share/xindy/lang/greek/iso88597-test.xdy
/usr/share/xindy/lang/greek/iso88597.xdy
/usr/share/xindy/lang/greek/polytonic-utf8-lang.xdy
/usr/share/xindy/lang/greek/polytonic-utf8-test.xdy
/usr/share/xindy/lang/greek/polytonic-utf8.xdy
/usr/share/xindy/lang/greek/translit-latin4-lang.xdy
/usr/share/xindy/lang/greek/translit-latin4-test.xdy
/usr/share/xindy/lang/greek/translit-latin4.xdy
/usr/share/xindy/lang/greek/translit-utf8-lang.xdy
/usr/share/xindy/lang/greek/translit-utf8-test.xdy
/usr/share/xindy/lang/greek/translit-utf8.xdy
/usr/share/xindy/lang/greek/utf8-lang.xdy
/usr/share/xindy/lang/greek/utf8-test.xdy
/usr/share/xindy/lang/greek/utf8.xdy