Ask HN: Anything to be done with lost Time Machine backup password?

My wife's macbook air was destroyed due to a watery-incident, and it turns out that the Time Machine password isn't anything that we can think of.

The computer was sent off to Apple for applecare+ repair, but when we got it back, the key is no longer in Keychain Access. It's gone.

Some of my students are cybersecurity majors, and they're doing a "class project" trying to crack in during downtime on our university's super computer.

Outside of just being bummed at losing 2 years of content, is there anything to be done that I haven't thought of?

Many thanks!