problem with ibus + XIM with emacs XT ?

[Madhu]

When trying to use XIM (Emacs*useXIM: true) with IBus with recent XT
Emacs (29.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo version
1.16.0, Xaw3d scroll bars) of 2022-01-04) I see that emacs does not
respond to some xkb input methods:
e.g.
 - ibus engine xkb:in:san-kagapa:san  Sanskrit (KaGaPa phonetic)
or  xkb:il::heb - Hebrew

For the purpose of this test, m17n input methods seem to work: e.g.
ibus engine  m17n:he:kbd

Can anyone else see this?  (Frankly I don't understand this stuff,
earlier, typically it was the m17n input methods that would not work, or
nothing would work, or some would work under gnome-shell/flashback but
not on plain X - and i put those down to bugs in ibus.  But perhaps this
is a recent regression)