I've had some correspondence with Stefan over the doors. The bottom line is that Ulf, the representative from the door company, still thinks that if we had oiled or treated the doors, we wouldn't have had this problem. But neither Wille nor I saw any instructions on the doors.
That said, we are in a pretty exposed and wet environment, and so Ulf is going to make new door fronts which are made of wider strips, placed vertically. This will greatly reduce the seams between boards which have allowed water to seep in, as we have seen in our current doors.
I'm not sure about having verticals on the doors, because we have a good flow with the current horizontal boards. But I was going to stain the doors and trim to keep them light, and let the rest of the house go grey, so there'd be contrast, anyways. And in the future, there are lots of funky new doors we could try.
UPDATE: Wille suggests to have the doorfronts sent to Jonny, the kitchen expert, and he'll keep them in his warehouse until Wille picks them up on his way to us over Easter. Wille will check with Jonny to make those arrangements.