Hi, I had already filed a bug report regarding this issue one year ago. It was a bug that had existed at least from Unity 5.
The support told me that they were working on the new input system, however, after checking the new input system that is currently in alpha, I don’t think this new feature is relevant to this issue. This issue is about Unity’s mishandling of IME, and the build-in input field UI and the editor input field are using the same system, they both exhibit the same bug.
I am developing a Chinese word game, and most of my players are using Microsoft Bopomofo to type Chinese. This bug is extremely crucial for me. I am still waiting for the official fix to this issue.
This was the thread that I posted one year ago:
Edit: I have just seen that Stephan_B said that he had resolved that problem. He was able to reproduce the issue when we discussed on my thread. So glad to hear that this issue would be fixed sometime soon. (although it has been another 4 months since the end of this thread…)