Not hard but tricky sometimes. I was worried my front caliper (Shimano Hydro) wasn't performing up to spec so I pulled it off and checked the pads. They were clean but one had some uneven wear so I sanded both lightly with 400 wet-n-dry on a glass sheet. Upon installation I noticed there was a lot of float in the bolt holes of the caliper and adjusted it so spinning the wheel was silent. It wasn't silent on the road though, a noticeable shick shick shick sound.

Then I read a few web pages on them and got my son to hold the front brake on as suggested and tightened the bolts. Quiet as a lamb, but on the road a very slight shick shick when I do a hard right turn

I have the tension plate installed correctly, obviously it's just super fussy. From my years replacing pads on cars and motorcycles I must say I'm a little disappointing in the loose setup of the calipers, the free-play in the bolt arrangement. To me it speaks of poor quality, a half engineered job where they had to compensate by drilling larger holes for the bolts. I have done that myself on one-off projects. It's the sort of thing you revert to when you screwed Up along the way!