When entering some text in a textfield over the remote keyboard plugin and you press Ctrl+A, it only marks the text on the phone and not in the input field in the plasmoid. When pressing backspace next, the text gets deleted on the phone but not in the plasmoid but only the last character there.
The keystrokes are forwarded directly to the phone, the view on the plasmoid should just be taken as a guideline but what actually matters is what the phone says. I would say there's not much we can do there... We can try emulating it but how far can it go? I tried implementing Ctrl+A, then other issues showed.