This looks like a bug. Could you please report it to bug-texinfo
(together with a confirmation that the cartouche problem has been
solved)?
It looks like I'd need to subscribe to another mailing list to do
that. Is this true, or can input be made without being subscribed?
You can submit bug reports without being subscribed; the list
administrator (also Karl Berry) eventually forwards your mail
accordingly after some days.
If I do need to subscribe, could I pretty please ask you to report
it and confirm the other bug fixed? I have a tiny test case that
can be submitted, plus details of a revision level that did work and
one that doesn't, which I can supply to you ready-to-go.
I can also do a bug report if you send me a small test file.
Werner