Get Kantar's Book on Blackwood.. it has 26 CHAPTERS on how to use Blackwood. Imagine, 26 chapters on such a "simple" convention!
I also would use 5
♥ here to ask for queen and others.
His responses to queen ask are (note, he doesn't ask for queen if there is a missing keycard, this is different from some people who are trying to signoff at five if missing the queen and a keycard):
- Returrn to the trump suit without the queen
- Bid cheapest side suit king
- Bid 5NT with the queen and a "useful card", he gives a list of what 4 things that a useful card can be.. .a) trump in partners first bid suit (he only bid hearts),
queen in partners first bid suit (not this hand, partner only bid hearts), c) extra trump in long trump hand (not this hand), d) if no side suit has been bid, queen in any side suit.... get his book
- Jump to grand slam if you can count to 13 tricks
For what it is worth, on this auction kantar response with openers hand would have been 5
♣ (1 or 4), and the 5
♦ would have asked for trump queen. Now 5
♥ would have denied queen, 5
♠ showed queen plus spade king, 5NT denied any side queen but show an "extra", not entirely clear what that extra would be from this list, but here with queens in two side suits and a singleton, must be fine to show extra that is not a king, 6
♣ = club king, no spade king, plus heart queen (can still have diamond king), 6
♦ = diamond king, no black king, 6
♥= heart queen, not side king, no "extra".
When hearts are the agreed trump, showing the spade king can be a problem. Not playing Kantar RKB on this auction of course, since the initial response would have been 5
♣ (which is why he rotates between 1403 and 0314) but imagine similar auction where the asking bid is 5NT... with hearts as trumps. He has rules for when you show the king (should you hold it), having to do with A) is asker known to have a balanced hand? Then show it.

does asker have a short suit? Bid in the short suit to show it. Know neither of those? Then don't show it.