This doesn’t meet your criteria because not FOSS, but hear me out…
I used synctoy for a while and it can sometimes be glitchy. I switched to aomei backupper [sic]. It’s basically shareware with a few nags. It seems pretty solid.
Only thing that I think would be better would be to use robocopy with the mirror switch. For help getting the syntax down and scheduling it with task scheduler, gpt3 should have you covered.
Robocopy is already built into win7, 8, 10, and 11.
For foss, I looked at bakula, kopia, and duplicati. It’s been a while since I looked into them so I honestly can’t recall why I didn’t switch to them. ¯\_(ツ)_/¯
Your scientists were so concerned about whether or not they could that they never stopped to think about whether they should.