I've had sellers mention to me that I shouldn't display artwork either, and, in my opinion, there's a difference between someone saying/emailing it and a pretty official looking document.
The letter that I received was in English, and an excellent translation from what may have been drawn up in Japanese. I presume this may be due to the fact that the seller at the studio was informed by the intermediary that the item would be going to the US. As I mentioned, in the wording of the letter, it's mentioned that the seller is aware that the intermediary is selling this item to another party. Since I still have a solid line of contact with the intermediary, I should inquire as to whether or not there is a Japanese version of the letter and if I can receive a copy of it. It'd be nice to have, even if for a reference.
It's also possible that the fact that the item was headed outside of Japan was the reason I received it. It's a lot harder to track artwork once it leaves the country and extremely difficult to legally seek its return. Anime artwork hasn't, as of now, been seen in the same light as say, Impressionism paintings.
As for displaying, it may be one of those things that, after many years pass, neither the mangaka or its copyright holders will really care. I mean, if you talk with young fans now about anime, they're pretty lost if you mention anime from the 1970-1990s. The younger generations, for the most part, haven't watched a lot of what you and I consider classics. They're into whatever is the latest and greatest(and not so greatest..) from Japan. So, twenty years from now, I can't see that there will be an extremely large fanbase for this manga as there is now.
So, who knows...maybe I can enter it in the 2040 Anime Beta Awards.
