That's a whole lot of uninteresting and irrelevant details right there.
Let's stick to the topic ("bolts should trace such a pronounced arc on such short distance") instead of being pedantic for the sake of it.
Especially since you nailed the point yourself:
But we are talking distances of mostly 30 meters or less. Neither bow nor crossbow would have any noticable arch. they will be about straight.
Mostly because, putting any realism aside, it just LOOKS BAD.
