I think other people may have mentioned this, but Tetra's modular tools aren't recognized by vivecraft, so items like bows and spears/tridents won't work properly. Additionally, all items (aside from the bows for some reason) aren't rendered as tools compared to other items, so they look odd.

To test this out, you can:

1. Hold any item (the hammer is the easiest one to obtain) and it will be rendered like materials.
2. Make a bow and try to pull it back. It doesn't give you the arrow for it, so it will not work. (EDIT: This only applies to bows in mainhand)

Bows not working is a much larger priority than the other things mentioned, but it would be cool if all of this was fixed.
If it helps, this mod added compatibility for better combat with tetra, so perhaps you could use the same method to recognize modular tools and give them the necessary identifiers so they work properly.

Ok, I have figured out a workaround for the bows currently in the game:

1. Hold the bow in offhand instead of mainhand
2. Hold at least one arrow in offhand (even with infinity)
3. Try and fire the bow and it will work

It is a little inconvenient, however this means that bows aren't entirely unfunctional and this fix isn't of high priority compared to other mod issues.