0.2.2 works fine.
I had those (actually 404 and 503) errors only whenever I tried to nest the pages 'Route (no spaces)'.
Does NOT work:
// Will fail with 404 error, because express route isn't registered.
// Will fail with 503 or at startup with ENOENT,
// because NodeBB tries to read 'gate/.tpl'
// Will fail at startup, because the plugin tries to create /nodebb-root/public/templates/secure/sales.tpl.
// I assume that fs.writeFile() doesn't create folders implicity.
Some more logic around library.js#L111-L121 should do the trick.
As for now (0.2.2), you'd have to go with simple routes.