Thanks for the suggestions. I ended up not trying Mindspell since they don’t have a trial version available and I didn’t want to spend $99 to look into it (though they also offer a monthly subscription through the Adobe add-ons website).

I ended up downloading a more modern comprehensive wordlist from https://sourceforge.net/projects/wordlist/files/speller/2017.01.22/hunspell-en_US-large-2017.01.22.zip/download Sidenote: the README for the default English Hunspell dictionary in InDesign CC 2017 says the dictionary is the 2006-02-07 release.

Then I’ll have the interested editors make up a list of other words they want to see and add it to the above list. I’ll use that to make an InDesign dictionary that all the editors can point to in their InDesign preferences.