Yes, the certificate is still provided! The Captain didn't bother to sign though.

I suspect I was the only person excited or possibly even aware we were taking the polar route alongside my travel partner whom I contaminated with my excitement! The English language announcement did not mention the route (I sadly do not understand Finnish), so it is only when I asked the purser who had kindly come to introduce himself about the routing that I knew about the route. There was similarly no announcement at the time of passing the Pole (nor should there be of course as most of the cabin was rightly asleep!), so I think that from that point of view, it's nice that the people who were oblivious to that little adventure could still get the certificate to feel they were part of it anyway!