It's supposed to be 75% the number of hits, representing the archers having to be extra-careful to avoid hitting their friends.
Those numbers are definitely screwed up. I'll have to check the code.
Thanks for this feedback.
Did anything ever come of this? Based on a recent battle in our realm, it's still the same as it was before:
Tuathal's Bows (6) fire carefully into the close combat near them.
Tuathal's Bows (6) fire on Monsters (7), scoring 1 hits.