Hello, and welcome!
The
ibus ports (which are available as installable packages) are:
ibus: the intelligent input bus framework
ibus-anthy: Japanese input engine
ibus-skk: Japanese skk input engine
All three of these are mantained by Federico G. Schwindt <fgsch () openbsd ! org>. You may reach out to him via Email, to ask if Chinese input methods for ibus are planned or in progress.
The Chewing inputmethod is available in both the
scim and
uim frameworks, as can be seen from
this conveninet list of the OpenBSD inputmethods branch of the ports tree. Kevin Lo <kevlo () openbsd ! org> is the maintainer of these two ports.
I don't use any of these inputmethods, frameworks, or applications, or languages.... so I do not have any specific advice other than to contact Federico and Kevin for their guidance. I'm sure they would be happy to help.