First off (not absolutely sure about this), I believe it is possible to install the 'standard' (American) firmware on an EU aircraft but I vaguely recall that one can't do it the other way around, though I'm sure someone will be along shortly to clarify this.
Height restrictions are the same whether it is EU or American firmware...alterable via the GUI if you have the right firmware...at least one version doesn't allow this. Not sure what you mean by 'mocked my location'. Surely the H would know where it is by GPS?
Finally, as @AeroJ asked...Why are you trying to bypass height restrictions?