My understanding in experimental builds is that bows and other firearms can no longer be “reinforced” like melee weapons, clothes, armor, and tools. Taking a soldering iron, sewing kit, or duct tape will not improve it beyond a light green/standard rating.
There are mods that can be attached to a bow to increase accuracy and the like, four in total if I recall correctly.
I know that arrow rest and bow sight are two of them. If you have the skill (fabrication, I think), you can craft these mods and apply them to a bow.
Crossbows are capable of holding other mods, such as those that are commonly associated with other firearms.