Slitherine

Obtained two bows with ridiculously big numbers.
This buff works - game freezes for a few seconds while trying to calculate area of attack and then lets to attack units much more further then it should be.
No special exploits are used, eg. Cheat Engine or smth.

Thanks for the report

We found a bug which would cause the behaviour you are seeing in certain circumstances. Easiest way to "fix" this bug until the patch arrives is to close and restart Fantasy General II as this will reset all items to the state they should be in and not use range extension items.
More technical information about this: If more than one influence adds range to your attacks the order in which these are added together will cause one of the corresponding values to explode into such huge numbers.

Same issue here, only that both my bows showed zero range
Reset worked.

Which units does this add +1 range for?

I tried on giant stone throwers, but they can still "only" throw 4.

Troll hurlers are siege, bows add range for missile