(I have not tested this since last year so if it has been fixed this post can obviously be ignored.)
I saw a post recently on Reddit where somebody had trouble setting up Chinese keyboard layout on Budgie. In short Ibus does not show so called candidates on Budgie, so it's only a problem for languages that need this feature, like Chinese, Japanese etc. The problem is explained more in detail here https://dev.getsol.us/T3066 and there's even a hacky solution how to fix it by forcing Ibus to restart. Not sure how stable that solution is though.
I was just wondering, should there be a little warning or something that showing candidates, for languages that needs this feature, does not work in Ibus on Budgie over at: https://getsol.us/articles/configuration/configuring-keyboard-layout/en
(Just to be clear, this is only the case on Budgie. I've understood it also does not work on other distros if Budgie is the DE.)