I think it would be a good idea if you could add the mandatory asterisk to the label of an input field in service studio as you are developing exactly how it would display in a browser if it were running.
I think it would give a clearer picture of how the screen will look when it is running. Similarly to how buttons now appear disabled in service studio and how the sort icon appears in tables, I think it would be a good idea to add an asterisk on the label if it's input field's mandatory property is set to true.