Hi
This kind of thing (two known words stuck together) happens quite often, most probably like BetterRed said, as the result of a botched scan.
I tried to make work the above function - I use a French dictionary with the Calibre spellchecker - but I failed (it reported it found nothing when I had a glaring example under the nose).
I probably missed something obvious. I use Linux Mint 17 and I have some Python inside it...
Could a good soul provide a basic example of this function that we could replicate and maybe a screenshot?