I disagree that the copying of callsigns is important if they are known in advance. Such would be the case in real organised Dx attempts and scheds
It is just a waste of valuable QSO time / bandwidth to exchange already-known information.
Why not regard the exchange of some unknown token as validating a genuine QSO?
Like a digit or two, or a single letter.
it could be a signal report, although a classic type of report does itself include a lot of known information in its structure and may not be robust enough
All a-priori information can quite happily be exchanged by any other route
Just because an IARU Handbook specifies something doesn't make it common sense - those rules / guidance or whatever were written by people who assume voice and the hand sent pulsed stuff is what everyone uses. Use for Contest rules, fair enough. But
real experimenters use their common sense
HOWEVER, I don't see the various deep search solutions in Opera including any unknowns in this sense. The time stamp is meant to act as that item of unknown,information, but is not being actually transmitted. Instead it has be correlated by external
means, which isn't quite the same in terms of strength of coding