create GUI
The advantage of the gui is that you can easily create a config without having to read the manual. So that the whole thing goes hand in hand with the previous architecture I could imagine the following:
there are 2 functions of the gui: a "config-editor", where you can create a new config and the user interface of the software itself. in the latter you could select one of the created configs and press a start button. the advantage of this is that you don't have to enter the data every time. also another gui would be possible but it should have all the advantages of a config file, so that you don't have to fill out the whole thing again and so on.