In the interest of fairness, I'll share a couple of things I've just read on the PC Engine's Japanese wikipedia page.
HE-SYSTEM is a "standard" (規格), and the logo is used for licensing purposes. In other words, it seems like pure legal branding and not like a real title for anything.
Also, the article talks about the Core Concept (コア構想), an official term that I know I've seen elsewhere. The idea, as we all basically know already, was to have one heart, or one driving "engine" at the center of a variety of peripherals including different media formats.
Yes, from day one, that meant the CD system.
You know, I can come out of this with a renewed appreciation and deeper understanding of Hudson's inspiration, creative process and marketing, including their attempt to expand the very definition of what a console could be into a new direction. Mentally, I have revised the assessment I made in the very first sentences of my very first post in this argument from "PCE and CD = One system? Not from a user's perspective." to "PCE and CD = One system? Not necessarily from a user's perspective."
OTOH, I still stand firm that Hudson's crazy dreaming, for all the wonderful things it gave us, did not always materialize into reality in quite the way they first saw it. Their visions were not completely consistent and went in a lot of directions at once. Their naming alone couldn't have been that good, or else I wouldn't have to keep typing "the Hucard system" or "the base PCE" or whatever just to make sure you all know I'm talking about that one square-shaped white-or-grey thing that only plays Hucards.
If you want to think of the base-PCE-Hucard system, the SuperGrafx, the CD-ROM2, the Super System Card 3.0, the Duo and the Arcade Card as all fitting into one tight PC Engine concept, I wouldn't tell you you're wrong. Even I like to shorthand a lot of things as "PCE" when I'm typing up a message. However, if you feel that in reality, the systems and libraries naturally separate out into at least two very distinctive groups, Hucard and CD, and if you feel that there seems to be an honesty and simplicity from a user perspective to thinking of things on these terms...well, I'd agree with you.
That goes whether you're a western gamer in 2016 or a Japanese gamer in the late 80s/early 90s thinking to yourself "57,300 yen? 1000x storage capacity? Separate and exclusive game library? Pop idols and anime girls galore? Peripheral my ass; this CD thing's a console of its own!"
(How much do you want to bet that if Sony unveiled $1000 peripheral for the PS4 that fractured it this much, people would lose their minds and refuse to accept it as just a peripheral?)
Also, if you want to tell me that the CD system, for all it costs and for all it provides, is ultimately no different from a mouse or a lightgun and/or does nothing for software but make it a little higher fidelity or whatever, I reserve the right to suspect you've been smoking whatever Hudson was when they came up with the Power Console.
Speaking of which, can-of-worms time: is the SuperGrafx really a PC Engine, too, or was it a separate console? Japanese doesn't have plurals, so I can't tell you whether it was supposed to be Core Concept or Cores Concept. Call me crazy, but I suspect it was supposed to be the former initially.
Anyway, in conclusion, rather than inducting a newbie by telling him to think of the PC Engine as being more like 1.5-ish systems and having at least two different libraries, I think I'll just start by telling him it's all a goddamn mess and he better brace himself.