I don't get this behavior. Returns create a new line inside the text field for me. Which version of Go are you using - iPhone / iPad? And are there any other conditions set on the field, like return to next field or something?
I have not looked into this deeper as yet, but I do know this much:
On some layouts it behaves as expected, but on one layout it does not. The layout in question is used in a script that is in pause resume state, so I will need to investigate further.