This is not directly related to NeoTrain, but is also an issue for other input forms in chrome on android with and external keyboard. I noticed it when activating "Wait on backspace" when typing the wrong char and then switched to "Wait for right char" and forgot about it. I found this https://stackoverflow.com/questions/22503559/backspace-not-firing-the-keyup-event-in-android-mobile and the link to https://jsfiddle.net/aravindbaskaran/33Snz/24/ - using input event it works ... Just want to mention it and do not expect a fix ;.)