Using the hopper ducts from hopper ducts mod, i tried every one of the 6 faces of the barrels and it didn't insert the item. I even added one item manually to see if it would accept it but it didn't. I tested them with a normal hopper and a wooden hopper on the top face and it worked. Tried the hopper duct again on top and it didn't. May be a problem with hopper duct itself or here. Ill open an issue on their end and point to here.
Mod version is the latest for 1.12.2

I'll add that i just tested some other blocks and it seems that the problem itself is with hopper ducts as it doesn't add items to blocks that doesn't have a inventory gui. Not related to Charset, so i'm closing this issue.