`cms.api` is in 2.4, right? I'm trying to push this into the 2.3 branch -- just had another page gone missing while we were chatting :)

The root cause of this bug is in `cms.admin.forms.PageAddForm.clean` which is manipulating OTHER title objects than the one it's creating. This is done within a code block that has the following comment:

> #Check for titles attached to the page makes sense only because
> #AdminFormsTests.test_clean_overwrite_url validates the form with when no page instance available
> #Looks like just a theoretical corner case

I really think what *should* be done is to fix the bug in 2.3 while changing as little as possible and then clean up `cms.admin.forms.PageAddForm.clean` and perhaps as you suggest test the multilingual system with `cms.api` and add some multilingual features in `cms.tests.admin`.