The index changes look fishy, too: Everything typeset in typewriter is
indented incorrectly by a space.
Regarding this one: My new best friend git-bisect says that
http://git.savannah.gnu.org/cgit/texinfo.git/commit/?id=0539d4e685a2185dd46d676d0b3f8862493bf8bd
introduced the misaligned index entries, which seems reasonable to me
(being a TeX-newbie...)
Thanks.
Maybe this interferes with the definitions in common-macros.itexi
that you already mentioned in your patch...
Nope, this can be reproduced with pure texinfo.
Werner