Maybe the Klingon we hear in the flashback is actually Tyler, ordered by Leland to "kill" Burnham's parents by faking their deaths and actually transporting them to Terralysium via the RA. Watching the most recent episode, I can't help thinking that Discovery will team up with the human-element of Section 31. Since we know that the RA can transport people, perhaps she (most likely Burnham now) transports Tyler to stage it and get her parents out to a place where no one would look for them, on Terralysium. If Spock participates with Tyler, it would be a meaningful gesture in restoring that relationship with Michael in saving her parents and letting them live out their lives there in peace. Maybe they were the original scientists on Terralysium who were referenced. It seems to me there's more to be revealed with that situation, in any case, especially with the revelation about Leland.