The Riverdeep Site contains some more information on the space fungi.
These fungi are growing on the interior, not the exterior, of the space station (I think most fungi would be greatly challenged to survive the vacuum, cold, and lack of water in space… except perhaps if they’re encysted in some way, and even then I’m doubtful).
I don’t know how likely it is that the fungi will survive reentry, but I’m doubtful that even if they could, they’d survive the splashdown. Relatively few species of fungi are marine, and those likely to have hitchiked a ride on the astronauts & cosmonauts are unlikely to be the few marine species. Of course, anything’s possible… from the Russians missing the ocean to parts falling overland to bits of the station or even just spores of fungi surviving.