I'm not an expert on your situation, as its a unique one. Having said that, if simply upgrading Ibus to a later version, you could run this is terminal...
CTRLAltT to enter terminal.
sudo apt full-upgrade
You will be required to enter your password, to run this command.
If the upgrade command does not upgrade the Ibus version, that means its not available in this distribution, and you will need to try another Linux OS that has it in its package manager.
You could try to switch from IBUS to XIM (maybe you need also to switch to Xorg at loginscreen to use XIM, I'm not sure because I'm not familar with that topic).
Go to settings > system > system > manage installed languages > language > keyboard input method system
There you see IBUS. Click there and change it to XIM, reboot and test