My experience with registered mail from oveseas is that it is slow. I agree with @lewm-- it's on a boat somewhere. And who knows was the post Covid/supply chain/etc. impact is even at this point. There was a period where regular postal business was non-existent between certain places for a while.
I got a fancy vacuum tube from India not so long ago- a week using the Fedex account of the vendor; ditto, DHL Express, for records from Japan. On the other hand, someone mistakenly sent me a record using Deutsche Post and it took a couple months. Hang in there.
Bill