Fit and finish on armory-quality bows? That's a little difficult to establish, because all the bows in question are over 500 years old, so all are now a bit wonky. However, back in 1995, I had the opportunity to observe/measure/handle the crossbow fragments found in the Padre Island (south Texas barrier island) archaeological dig. With the exception of the steel prods (@20 in. long) all the metal was gone, but the inlets for same were informative. Lockplates and cheekplates (at the fore-end, these are the skinny Spanish bows) had been riveted in place, and x-rays showed the rivets were not square through the stock. The lock and cheek plate mortises were slightly different sizes as well... with 1/8 of an inch, but not quite identical. The roller nut on the best preserved stock was a tiny bit off as well. The bone nut, @ 1 inch in diameter and 15/16ths of an inch wide, had the lugs and space between divided evenly, each 5/16 in. Except the right lug was a hair narrower than the left. The trigger had some manner of wedge or perhaps a bone/horn spring to keep it engaged... that shows up faintly in the x-rays. Also the nose-ring for hanging (this is a gafa bow) had been put in crooked, then removed and re-set at the proper angle (again this shows up in x-rays)
As for fit and finish on extant complete bows, perhaps the crossbows in the armory at Malta would be worth studying. Also Schloss Grandson, in the Tyrol was the Von Trapp family hunting lodge. They have a bunch of nice quality gents bows in the armory. Not fancy Rolls-Royce stuff like Ulrich V bow at the Met. These seem to be more Buick-Toyota nice quality loaners for friends who came up for the hunting.
In short, I think issue stuff was expected to be clean, tight work, but minor blemishes weren't necessarily a deal breaker. DRW/Geezer