Проблемы с фокусом при нажатии на Enter в EditText

Возможно вам поможет android:nextFocusDown https://developer.android.com/reference/android/view/View#attr_android%3anextFocusDown

Defines the next view to give focus to when the next focus is View.FOCUS_DOWN If the reference refers to a view that does not exist or is part of a hierarchy that is invisible, a RuntimeException will result when the reference is accessed.