Enter in VBScript vs. in InputScript: I have been struggling a little bit with the screen & enter commands in combination with CallVBSAsync / ApplyGuiScript. It seems to me that when there is an "Enter" performed in VBS then I need to insert an extra "Screen" command into the InputScript in order to continue processing.

Your approach is correct. If the VBS executes the "Enter" you don't need it in the InputScript, but for the next screen displayed you need an additional "Screen" command.