But could they expect her to die so soon? Could any of them expect Onni to find out what's happened to her?
Taru likely could expect that of Onni, being Finnish and knowing how things tend to shake out in their culture/spiritual system - she's a former military strategist, she ought to be aware of the capacities of mages if she was any good at her job at all, and she wasn't particularly fazed to call out Torbjörn on the "struck by lightning inside the house" thing. Trond is a wildcard - but he's Norwegian, so he ought to at least believe in magic even if he's unclear on the Finnish system. Torbjörn and Siv? Not.
As for expecting Tuuri to die so soon... no. I don't think so. It must have been around ten days -possibly longer - since Odense, so she's perfectly in time for
showing symptoms (two weeks being the normal quarantine duration), but Hilde Rasmussen lived another two weeks after showing symptoms, and it's been implied in the hospital flashback that people may survive longer (and then trollify), so Tuuri would have had time, physically (the voices are a different question, she may not have been herself), and it sounded like they were expecting her to make it to the ship from the last radio interaction there was. It also seemed like they were harbouring some hope that she might have gotten away somehow. Her suicide was out of the blue, and will probably be received as such.