This mainly does not seem to be a Hype related issue.. have you asked on any Andriod/iOS dev forums/ stackoverflow ..?
Reading again, it looks like you are trying to communicate between the Hype scenes in a webview and the Andriod app/system.
Is that right.
Doing so with iOS is possible to some extent..
If the Android API allows javascript messaging between the App and a webview then you may be able to tap into that. But even if you can that may not mean you can go outside the Apps sandbox and access systems like soft keys...
Doing a quick www search shows that Android employs the javascript API that is used with iOS ( as above )
See..
https://medium.com/@elye.project/making-android-interacting-with-web-app-921be14f99d8