Almost every paragraph has multiple technical errors of a fundamental nature.
" ... but it was equally capable with AM (about 510 to 1620 kilohertz, which was referred to as “medium wave” in olden times), and the spectrum below that once quaintly known as long wave (148 to 420 kHz), and also FM."
AM and FM are modulation modes, not frequency bands. For example, most shortwave stations also transmit in AM. And on course FM is used in many places besides the VHF Broadcast band.
The Medium Wave and Long Wave bands are not "quaint". Those are the international designations for those particular wave bands.
"The preselector is a mechanism for filtering out frequencies that are closely adjacent to the frequency the operator selects, minimizing the potential interference from other signals on those nearby frequencies".
Completely wrong. Close in stations are removed by the main IF filter. A Preselector is a manually tuned RF stage which is intended to remove Image frequencies and other spurious responses.
And to say that a Preselector is "rare, possibly even unique" is utter nonsense. Good quality radios have an automatically tuned RF stage, it's only in cheap radios that a manual control substituted.
And it's a Band-Pass-Filter, not a Low-Pass-Filter.
"Hams on various Internet message boards argue about the relative technical merits".
No they don't. This is not a specialised Ham Receiver. It was specifically designed for Short-Wave Listeners.
I could go on.