I sent Grev (France ==>England) two tsuba at the end of last year, the package disappeared after 10 days of the tracking system, I did inquiries, it seemed they were in England. The package was « lost ». Grev did a reclamation, the package was insured, I did the same with French Chronopost, they had 30 days to find it, otherwise they had to pay. A week later, Grev was at home when he heard the door bell, and here was the package. It seemed tha someone had step on it. The package was for three months in a no man’s land, somewhere between France and England.
Same thing with Germany but for a juyo sword, the package disappeared between French post and Bundespost, Same thing, disappeared from the tracking system. Same path, reclamation from both the sender (myself) and the sendee. It reappeared 3 weeks later, the package had a nice koshi zori. By chance, the sword did not suffer from the post mishandling.
Last example, I order in England a fly fishing spare spool for one of my reel. The store send it to me at once by register mail with tracking. It arrives in France and then disappeared from the radar. The store reimbursed me last week after receiving the package in return after a fake delivery at my address saying there was nobody at the address, that they have noticed me this attempted delivery and tha I did not come to fetch it at the PO.
so there is a great chance, your package will reappear along the line, but the sender as well as yourself must raise hell.