I'm not sure if there is a fix for it but a user can spam click sell item and recieve more emeralds than they are supposed to as there is no code for disabling the sell button before the item is removed from the shipping box inventory

For anyone still interested:
https://youtu.be/4YIxM_HAcmQ

By using autohotkey or an equivalent to spam the mouse button, you can very easily get over 64 emeralds for a single half stack of any tradable produce. A single sugar cane farm can provide enough emerald to power your entire base using Thermal Expansion

This has definitely been around for a while..
Is there any news on if this is going to be fixed?

Also running into this issue in my modpack. Maybe adding some kind of cooldown between trades to stop this glitch?