As a native Dutch speaker this is killing me. Impenetrable Dutch. I can confirm what they’re saying is true though, it is notoriously difficult to pronounce—but you don’t need perfect pronunciation to be understood, and you can get by with just English grammar especially if you’re using it as a secret language. I don’t know if I’m fully convinced it would be a very good secret language, as Dutch has a lot in common with English and it’s not that obscure due to its similarities to German as well.
Either way I hope for more Dutch mentions, maybe even Dutch dialogue, so I can giggle. The language spoken with an American accent is just about the least Dark Academic vibe I can think of.