Off by one, on the string
Archery was the part of a friend you could not see. Their bow came up, their arms drew, and the arrow appeared out of nowhere the moment it left the string.
The arrow on the string
The mod now tells the other game when an arrow is on the string, and the other game puts one on the bow it shows.
The first try put it there point first. An arrow's model starts at its head, not at its nock, so an arrow placed "at the string" had its point at the drawing hand and the rest of it sticking out behind the archer by a whole arrow's length. It is placed by the nock now.
One too high
Then the arrow appeared only once the string was fully drawn, never while it just sat there. The game counts a bow's state in steps: 8 while drawing, 9 with the arrow on the string, 10 fully drawn. We had the list one place off, so "arrow on" went out at 10. It goes out at 9 now.
Status
Seen in a real session on 15 October: the arrow sits where it should while the string is pulled. In the build we are testing, not yet seen for real: the arrow resting on a string that is not drawn yet, the string itself pulled back to the drawing hand, and a bow that is already drawn when your friend joins. An arrow you hold in your hand before you nock it is not sent at all yet.