Hi FrankRaij!
You should use InventTable to make links between CustConfirmTrans and EcoResProduct/EcoResProductTranslation:
CustConfirmTrans.ItemId == InventTable.ItemId
InventTable.Product == EcoResProduct.RecId
EcoResProductTranslation.Product == EcoResProduct.RecId (or EcoResProductTranslation.Product == InventTable.Product)