As of Mp3tag v3.35-beta.2, these are the untranslated strings for the Bulgarian localization of Mp3tag.
_C_OPT_FILES Files
_C_OPT_FILES_FRM_READ Read Files
_C_OPT_FILES_FRM_RENAME Rename Files from Tags
_C_OPT_FILES_FRM_WRITE Write Files
_C_OPT_FILES_ST_REPLACE_FOLDER_SEPARATOR Replace folder separator in tag values with: