I would try writing the support about this, maybe they can include an update in the next release. Sadly, there is no bug tracker for the FP that I’m aware of to fill in a ticket for this “outside” of the FP support. I just asked for something like that a few minutes ago:
Bug Tracker for FP1 & FP2 software
Time to build your own, that’s what FLOSS is for 
I’m sure you can find a Finnish dict and somehow port it to Anysoftkeyboard in the meantime. It’s a good training to get to know your phone … 
This sounds useful, but I guess the new code is on git hub, maybe these links will help building your own?
https://code.google.com/p/softkeyboard/source/browse/trunk/DictionaryTools/
And on your own risk:
https://softkeyboard.googlecode.com/files/ASK_Swedish_20110712_2.apk
Maybe there will be an ROM update to FP1 soon. We can still hope!