Equations and graphics in HTML output from FrameMaker are blurry images

Just to hang these remarks where they might be searched on, I was just playing around with the legacy Eq palette in FM2020, and discovered that, to PDF output, FM is rendering Equation special characters and operator symbols
  as BMP Unicode, in PUA space (U+F0xx range),
and not, as I might have expected,
  as Latin1 codepoints with font Symbol applied.
Interesting. Here's an example:

In legacy FM, using character ⊗ in user text would have been:
Latin1 "Ä" (\xC4) with codepage/overlay font Symbol applied (circlemultiply).

In FM8 or later, one might have expected the Eq palette to use:
⊗ U+2297 CIRCLED TIMES
(and all the instances of ⊗ in this reply are U+2297)

But what FM2020 renders into PDF is:
⊗ U+F0C4 {unnamed Private Use Area codepoint}
and presumably with an embedded font with the glyph for that. The C4 is likely not coincidental.

Now, for extra weird, the FM7 (2002, pre-Unicode) Character_Sets.pdf document, which, based on the metadata, was authored in FM6, contains a ⊗ character that's encoded in that PDF as: U+2297 (the proper Unicode for that character). So some Unicode work must have been going on for FM well prior to FM8.

Why didn't the Eq palette shift to stock Unicode at FM8? Possibly because no font at that time cleanly populated all the needed code points, but perhaps more seriously because at least one of the needed code points was above U+FFFF (into the SMP code space, U+10000 & up), which FM didn't support then … and still doesn't (FRMAKER-10976).