Generally customs only comes into play for the receiving country, not the shipper. For it to take this long they didn't ship them individually. They chose to ship them freight or cargo and then reship. That's the only explanation. Assuming they actually shipped them. A handful of people on china claim to have them. And they one guy who ordered several only received one machine and confirmed that anyone else who ordered several also only received a single unit.
What you can export, in what quantities and to where is something for which each country has its own regulations - things can and do get held up in customs in their country of origin (even using a customs broker doesn't guarantee this won't happen, especially with products being exported for the first time).
They already said prior to CNY that they had shipped 53 units in one batch and were waiting to learn whether those units had made it out of China before CNY. It would be silly to ship more units by the same route/method before knowing the fate of those 53.
Yifu has made very clear in past posts that they are hoping for people to become Avalon re-sellers, which could make the shipping process much easier for future batches.
I agree that Yifu needs to provide an update on this, but comparisons to other products for which the customs issues were solved long ago are pretty meaningless (hell, even things which should have no customs issues whatsoever randomly get held up, no matter which carrier you use).
