This class isn't needed anymore now that $FG_ROOT/Translations/default/sys.xml has a flat structure, like the other FG XML i18n files that define the default translation. This is related to https://sourceforge.net/p/flightgear/flightgear/ci/6d6e1809f00e3e2fa4e3f3dbf78967a39c474af1/ and more specifically to https://sourceforge.net/p/flightgear/fgdata/ci/587c60134585429921b998cb824abed01c6c475d/