Hehe, ok. Well, I can't speak for every English speaker around the world, I can only suggest the ways in which I, as a native, understand 'hard' and 'difficult' in this phrase.
Personally speaking, I'm pretty sure I use both about as often as each other, and that I hear both about as often as each other, and to my mind they seem completely interchangeable in this phrase. After all, something that is 'problematic' and something that is 'intricate' can also be thought of as difficult, no?
I don't want to split hairs, I just disagree a little with the complication in this instance.