I suspect that there is no official answer to this one, simply that if it felt hard then it was, so get it checked as a precaution. That said, I have some old training guidance notes that stated:
"Aircraft are certified for landings at 600fpm at max landing weight and 360fpm at max take-off weight"...
"A normal landing is 120fpm".
I must admit that until I had read this, I had thought that a normal (ie good) landing was almost zero fpm. Notice no mention of "g" which is just as well as my estimation of "g" is probably worse than my estimation of the flare height !
S & L