Some crude nickel tests follow for this 3.5-year old(?) keyboard:
backtick/tilde key that i hardly use:
bounces back from 40g, stays down with 45g, actuates with 75g
numpad5 key* i hardly use:
bounces back from 35g, stays down with 40g, actuates with 70g
up arrow key:
bounces back from 25g, stays down with 30g, actuates with 60g
spacebar (same from center and sides):
bounces back from 25g, stays down with 30g, actuates with 65g
e key*:
bounces back from 30g, stays down with 35g, actuates with 65g
i key*:
bounces back from 30g, stays down with 35g, actuates with 65g
s key*:
bounces back from 25g, stays down with 30g, actuates with 60g
w key*:
bounces back from 30g, stays down with 35g, actuates with 70g
* for these, i had to place a cardboard shim underneath the nickels so as to not press adjacent keys