Could you describe your paintings; are they framed? what size are they? On paper, canvas or board? If large-ish, would smaller paintings be cheaper for you to post?
Bit difficult to compare my UK postage facility with the Finnish one, but we have (generally) three options for international delivery; untracked, tracked, and tracked + signed. The advantage, I guess, is that tracking does help to pinpoint things if a parcel goes astray en route to an overseas destination…especially if the artwork is a bit more expensive.
Does the Finnish system offer compensation for lost parcels? The amount will (perhaps) vary according to the service you choose.
Since I don’t know the Finnish postal rates, I can’t suggest much else other than perhaps forget framing (if you’ve done that), create smaller pictures with less weight, etc. It’s a difficult position to be in.