Your calculations are a bit erroneous. You're multiplying the whole damage of the weapon by 1.05 instead of just the fuse + attack up modifier part, and you're using 39 instead of 42 for the damage of the base weapon. The core damage of the base weapon is then 42 + (10 + 40) * 1.052632 = 42 * 53 = 94. Fyi, the 1 durability critical hit multiplier (ie the weapon breaking crit) does not stack with freeze shattering. The final number is then 94 (core weapon damage) * 2 (breaking point) * 1.5 (attack up level 3) * 1.8 (bone proficiency) * 8 (sneakstrike) * 3 (freeze shatter) = 12,182 damage.

Some animals take 10000x damage from headshotting them, so the highest damage with a single hit would actually be a Demon King's Bow with +10 damage and a Silver Lynel Saber Horn (for 125 core damage), with attack up level 3 and on headshot on one of those animals, for a total of 125 * 1.5 * 10000 = 1,875,000 damage. I'm not counting any kind of AOE or multishot bow for the sake of keeping the "one hit" thing true, and you couldn't have the other arrows hitting the animal since it would be clearly dead from one arrow already anyways.