Message saving does not work but the extended editor does not reflect it.

How about improving the "invalid token" to something directing the user to a more helpful action? Such as: "invalid token. Your edit is not saved, but may be buffered locally. You need to open a fresh edit window; then copy your edit to it, and save it if you wish."

The new translation editor is supposed to fix this.

And now it does as far as I know. Markings this as fixed as we are not going to fix this in the old editor.