I just ran a spellcheck on Project Quintessence part 1, and even not counting the few lines of non-English dialogue and the character names, there were ten times as many real words it didn’t recognize as there were spelling errors.
Here’s a partial list. For things like religions and sexual identities, saying that labels people call themselves by aren’t words is both an example of and could contribute to “invisible minority” issues. (Unless it was done on purpose; in that case it would be directly insulting. But I’m assuming no real word was thought of and then still intentionally left out.)
Words I think it’s especially unbelievable that it didn’t recognize are in bold, and words that WordPress doesn’t recognize either are in italics.
Common words and slang:
forth (as in “back and”)
Just a few of the many compound words it wants to uncompound (to be fair, “uncompound”might actually be one I just made up):
Kinsey (as in “Kinsey scale”)
Higgs (as in “Higgs boson)
most constellation names