Got it, thanks! It worked out at the end when I downgraded everything to match the documentation. I had trouble finding the old Android sdk tools, where the 'android' command was not deprecated (25.2.5) but now I found some links. Cordova 5.4.0 works with the Android WebView.
For anyone that might have a similar problem, here you can get the older tools -- https://forum.unity3d.com/threads/solved-android-command-deprecated-error-unable-to-list-target-platforms.458814/