@yyp As far as I know for java you could use -target 1.1 with javac. But well the only javac I got was an old version of eclipse-ecj (as I failed to bootstrap OpenJDK).
And failing that it should still be proper documented so it can be remade for modifications when needed (in fact Guix and quite few other distros keep ancient versions around as mere build-dependencies).
And recipes are required per GPL, at least GPLv3's "Corresponding Source", which GNU gettext is licensed under.