How good are the engines that are created with Yould? Here a good way to find out:

First, create a complete word list used in an engine
yould -t cicero.yould -s > wordlist.txt

Second, generate 100 words with the engine using –real-words flag
yould -t cicero.yould -r -n100 > co100.txt

Third, sort the 100 words in alphabetical order
sort co100.txt > sco100.txt

Fourth, run a comparison that prints out only the words in sco100.txt that are not in wordlist.txt
comm -23 sco100.txt wordlist.txt > compare.txt

Fifth, count the number of lines in compare.txt
wc -l compare.txt

You can script this as well, just needed to make some notes before doing some explanation later. This works on Windows if you use unixutils from sourceforge. Very handy toolset to have.