If the items are detained by customs after the ship left the seller's country, then the buyer is responsible for clearance of the detained items.
It is the buyer's responsibility for any custom duty fee that might be charged from delivery. How the import duty will be charged depends on each country's custom policies.
Usually we will write less than 22EUR declared value in the package, so almost all packages will be tariff-free (but can not guarantee that all the packages),If Customs requires purchase invoices, please contact me and I will send you by mail electronic invoices.