Is it possible to modify the LoginButton text using a NativeScript property?
The LoginButton component is a NativeScript wrapper of the native Facebook LoginButton controls defined in the Facebook Android and iOS SDKs. Currently, these SDKs do not expose any methods for changing the text of the native controls and it is not possible to expose a NativeScript property for changing the button text. As a workaround, you could always use the custom user-defined button approach which is fully customizable.
Why does the login window disappear without any errors on a real Android device?
The init method of this plugin requires a Facebook AppId. In order to get the login flow working on a real device, you should register your device key hash in your Facebook App. You could find more details here.