After a looooooong (~7 weeks!) time, I got a reply:
You are enrolled to the tier match campaign. We can offer you status match as follows:
After first flight points are credited to your Finnair Plus account, you will receive Silver tier. New qualifying period starts and you have 6 months time to collect 40000 points or 23 oneway flights to be upgraded to Gold tier.
The first flight needs to be Finnair, others can be oneworld flights.