Depending on the distance the force is dissipated over, 500fpm would be around 1.5 to 2g’s. Last hard landing on my fleet showed slightly less than 500fpm descent rate, no flare, deceleration at impact was approximately 2.1g.

In other words, if a 777 autolanded at max landing weight at 500fpm, it would likely be considered a hard landing and require an inspection.

Not aware of a number published for Autoland for 757, 767, 747-400 or 747-8 regarding descent rate at touchdown (AFM, FCOM, FCTM). No knowledge of 777 however. Autoland descent rate is minimal at best.