Geezer here, with observations. Even with the simple 'tickler' trigger of the one-axle roller-nut crossbow, there's much that can be done to improve release. Over the years, I have learned to position the pivot-pin the distal end in a straight-horizontal line with the sear. The further aft you put the pivot, the quicker the distal end (bit that goes into the sear) moves, but the leverage will work out to more work. The further forward you put the pivot, the easier the pull on the tickler, but the movement of the distal end will be slower... it's simple leverage. Placement of the sear in the nut effects release. A sear on the precise bottom of the nut (as shown by Payne-Gallwey) along with a very slightly arced distal-end on the tickler, will reduce the effort and smooth release. On the other hand, moving the sear back a quarter inch, so it's a bit behind the bottom-center will substantially reduce the pressure of the nut trying to rise out of it's round socket. That gives you longer lock-life and reduces the tendency of the nut to tear out the back of the socket on release.
With the complex multi-lever releases found on sophisticated Renaissance crossbows, the sear is moved to the back-surface of the nut, so the nut is held into its socket by the cam-action of the last bits of the lever-train. That means the nut-socket, which fits the roller closely at the front, can be quite loose at the back, so there's no strain there. You will note that nut-sockets are commonly heavily reinforced with a big chunk of bone or antler at the front, but the back 'lager' block is normally much thinner, or even absent entirely. All the rear 'lager' block really does in one of these complex locks is provide a low-friction surface. Of course they hang the roller itself on the 'nussfaden' cord, to keep it from oscillating or jumping out on release, but in fact the 'nussfaden' doesn't actually bear any load when the lock is set... it only keeps things running smoothly aftger release.
Like I say, it's complicated. .. Does the above make sense? Geezer