They do have to ask for the FIA and other teams/manufacturers get to see the plans/proposed change, but copying seems unlikely given the differences between the engines and the cost associated with changing something if you've gone down a completely different direction.
It's been that way since the v8s came in to force and we haven't heard about engine technology being copied, even when Renault were behind (yet again).
As was said by Anthony Davidson, during the last Sky FP, part of the reason the Honda engine struggled in the later years was that they were too honest. i.e they only brought updates to improve reliability, where as the other manufacturers were improving power and efficiency too.
I also heard that Honda were a very proud company and didn't ever want to see one of their cars of engines grenading itself live on International TV so would over engineer and restrict the engine on a regular basis. They reckoned it could have easily run another 100HP over what Honda would only allow it to run at but they were afraid of losing face on TV.