This sort of thing has stopped me from selling models abroad. EEC law states that the seller is 100% responsible for any damage or loss incurred. Transit insurance is ridiculous and a lot of them (couriers) say they don’t pay out on the first £200 of damage anyway!
You can’t win. If it is damaged, they will say “insufficiently packed, or it wouldn’t have got damaged!”
Another “get out” statement is, “The recipient had got rid of the packaging, so we couldn’t check!”
At the same time, the EEC DO NOT force any rules on couriers. If it was made law that if you pay a courier to deliver something, they are legally bound to make good any loss or damage, maybe they would look after things better!
I would NEVER entrust anything delicate to Royal Mail. For my UK deliveries, I have used UPS for several years and they have never lost or damaged anything so far. Quite reasonably priced as well!
Bob