/usr/lib/mono/4.5/I18N.West.dll is in libmono-i18n-west4.0-cil 3.2.8+dfsg-10.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/mono/4.5/../gac/I18N.West/4.0.0.0__0738eb9f132ed756/I18N.West.dll
/usr/lib/mono/4.5/../gac/I18N.West/4.0.0.0__0738eb9f132ed756/I18N.West.dll