I have a possible solution but I can't figure out how to post it here without spoiling it immediately. If you tell me it's OK, or if somebody tells me how to post text with a black background (so you have to select the text to see it), I'll post it.
Using dpaste is a great idea! But I just realized that I was reading the clues wrong -- I thought the gray tiles were the user's attempts, not clues that the game gave you as already correct. It does indeed look like a bug or it's using a very obscure word.
Sorry!