What I could easily do is to use my Finnish frequency data and this speller to list words that are not accepted and the alternatives given by it.
If a native Fin could check these words for missing ones, a good enough speller could be made. I would be willing to discuss compounding mechanisms to see if it is really undoable.
First thing I see is that there are at least 100.000 word forms I found that are well documented in a dictionary, but not accepted by the spell checker, some with a very high frequency. These need a manual check.
Second thing that I see is that : is not a word char in the speller, while it is clearly in some (spelled) words.
@aaron-hall: I might be able to help your company in some way or other.