I think you need to update to your post. There is absolutely no evidence that google play codes OR XML will redeem in HD so saying may or may not is completely misleading. I know it sux as a seller that all these codes were dropped to SD, but some buyer should not have to pay for that problem.
I had an XML code transfer as HD recently (within the past couple weeks after the supposed changes). I'm not sure if it was originally supposed to be an HD code, though. It was for Diary of A Wimpy Kid: Dog Days