When I type quickly I often hit on key before properly releasing the next (I am a terrible typist in other ways too, chances are many other people are likewise!). This seems to make your code think I've accepted the current suggestion so I end up with extra words embedded in what I am typing, for instance "test" comes out as "termst" if the bad key event ordering occurs with the e and s keys.

It works great if I make an effort to properly release one key before touching the next though, and I suspect this problem could be checked for and mitigated with a little extra logic in your event handlers.