Did you consider getting some other people to do this manual curation process? You could then use roughly the intersection of all lists.
In practice, the way I approach this is by reacting to complaints from players who either don't know words I included or were disappointed I didn't include a particular word.
That said your approach seems to have worked well. Kudos!
The best I could come up without going through the dictionary word-by-word like you did was to use data from actual games played, to see what words were actually being found by the players.
Here is the word frequency from about 900 days of daily challenges (about 15 players per day), ranging from TEE found 4636 times to LAWYERED found once: https://docs.google.com/spreadsheets/d/1OY32E-JyHh2C4A_1ADy4...
In this game the goal is not completion but to get a high score that you can compare against others (and yourself from previous days). So far I haven't done much with the list of word frequencies except an experimental feature where you can see stats about your game using "commonly found words only", e.g. what percentage of commonly found words did you find.
You can try the game here: http://crosswordislandhopper.com/playGob And the daily challenge: http://crosswordislandhopper.com/dailyChallenge
Perhaps words in this category should be on a banlist where you never generate puzzles where it would be a valid guess.
