Hi Ben,
Yes at the moment the overlay text in the pro gallery is not responsive,
I understand the workaround you were going for, but you cannot cancel the “mouse in behavior” of a text element, nor can you go to expand mode using code.
One option I can think of is to use it as it is with the text overlay (does it have to be responsive in size?) and BTW you can give a different font style and size in the mobile view.
another option I can think of if you want full responsive power is to use a repeater and create your own “Custom” pro-gallery. this will involve some code.
We are always working on improving Editor X so I will forward this feedback to our product team.
Thanks,
Ido.