Is it safe to order a Huma moderator from Huma to the US?

Sorry, I speed-read your first post and missed the part about you wanting moderators.

Some time back (maybe last Aug or Sep) there was some discussion on AGN regarding a revision of policies at U.S. Customs which was impacting the importation of air gun moderators, as well as some air guns which had moderators. They were not being allowed to proceed, but being 'turned back.'

A little later there was discussion on the site that Krale was no longer accepting moderator orders from U.S. customers.

My personal experience is that I ordered a specific Air Arms moderator from a U.K. dealer, and it shipped about the middle of last August. Spent a good amount of time in USPS Status 'Processed Through ISC Facility' (which actually means arrived at that facility), then the status changed to 'Inbound Out Of Customs' on 10/14/2020. And that is how it has remained to this day.

The vendor already refunded my money, so I'm not even following the shipment any more. Was it lost by the USPS? Did it get stopped by U.S. Customs because it contained a legal air gun moderator? If Customs stops something 'illegal' do they return it to the sender, or seize and destroy it? 

I don't know the answer to any of the above questions. All I know is that I never received my moderator ordered from Europe last August. I don't think you have to worry at all about an Alphabet org door knock, but as far as receiving your purchased item, YMMV.

I have found Huma-Air to be great communicators. Drop them an email - If U.S. Customs is causing issues with legal airgun moderator shipments, they would know.

I have something ongoing that MAY be related. I ordered some spare parts for the LGU/LGV from John Knibbs in England (airgunspares and thecountrystore are other business names they operate under, I believe) at first of April. Included in that order was an HW44 moderator. That order shipped from them in less than a week and arrived at a similarly titled facility to the above in Chicago on April 6th. Tracking shows that. Since then, NO updates, no indicated movement. Emailed Knibbs this week and received a reply that THEY cannot locate the package through their "ROYAL MAIL" system and that their linked USPS follow on shows nothing. They note a refund would be given "for any package returned". Not a problem they created but not particularly helpful either. Seems it might be related to the OP's question. 

My concern is-if "the powers that be" are involved and are so concerned about something usable ONLY ON an HW44, how long might it be before some other "more flexible application" units from Europe OR EVEN from inside the US are possibly targeted as well? Hope this isn't the case and that it's just a lost package, but it seems to be a potential concern.