Treasury's OFAC (Office of Foreign Asset Control) has been the organization that I look to for what's legal for travel to Cuba and importation of Cuban goods. It seems clear to me, and that's why I went to the Treasury website for clarification, but a legal eyeball wouldn't hurt. I won't argue with Andy, but pointing him to a better source may change his opinion.
I'll take a shot at openly importing a box in 5-6 weeks and let you know how I make out. The "acquired in third countries" phrase, which I underlined below, seems pretty clear to me, but you never know - I've seen an attorney argue that "free doesn't mean free".
Persons subject to U.S. jurisdiction will be further authorized to import Cuban-origin merchandise acquired in third countries into the United States as accompanied baggage, again without value limitations.