Parallel imports are never unlawful ----not to U.S. So far, no case rule against it.
But it remain questionable in some E.U counties. So, it is prohibited in Hong Kong and Japan, two I am very sure.
However, in the international law and trade level, nothing against it.
About a resell and proxy, a good law person can always argue about it, in fact, it just depend on that way of contract. A clear line is that, for resell, you first own the product and then sell it for profit. Normally, for a B2C selling, seller don't have to know buyer ahead, it just put it up for sell.
But proxy is different, proxy collect buyer information before they purchase product, and hand out buyer information directly to seller, the proxy agency usually do not have the ownership of the product at any point of the sell. So, the actual end user will indicate on the invoice upon need.
anyway, the fact is, no matter parallel import or proxy, as long as not involved dumping, it is commonly accept among business.