Anecdotally I have heard of students having trouble figuring out what the terms mean. You're even admitting it yourself -- if you have to rely on looking them up in the dictionary then it's obvious they aren't obvious terms! No one has to look up "allowlist" and "denylist" because they do exactly what they say on the tin.

You have yet to give one valid argument as to how "whitelist" and "blacklist" are better, and indeed, have unintentionally given one argument as to how they are worse.

And yes, they are strictly engineering terms. Merely appearing in a dictionary doesn't mean they aren't. Most technical words are in the dictionary despite not being used outside their fields, e.g. here's one: https://www.merriam-webster.com/dictionary/stator