If the accuracy of thrown weapons is determined strictly by range, this may go some way to explaining the absolutely absurd accuracy the goblins have with their bolas, seriously, they have a hit rate in the upper 70’s with those things at the outer edge of that range during daytime, but they won’t use them at all during night (I’m guessing this is because the AI knows the chance to hit and therefore assumes it’s a waste of time).
In the scenario at least, I noticed that the goblins accuracy with bola is okay, pretty hit and miss. It’s just really devastating when they do because the bolas reduce both defence and attack. It’s possible you just had a bad round of RNG.
I’m more concerned with those darned shaman – there is absolutely no way to resist being entangled by roots every round and the shaman doesn’t get tired doing it. Fortunately there is a work around to reduce the effect by separating out the units so that entangle only affects one unit at a time.