Can any Blueprint experts tell me whether its possible to detect keypresses in the Construction Script without resorting to Editor Tick?
You can’t detect keypresses at Construction Script.
You can do the following:
Your construction script instead of having a bunch of code, you just call a function, lets say MyConstruction. There you will put everything you have in your current construction screen.
At the Event Graph, whenever there is a keypressed, just call that MyConstruction function and you are done, probably will need to add parameters like the key pressed etc.