This is from Jacob Poon's report of 2007-10,
https://savannah.gnu.org/support/?106274

The letterlike range has design issues, because it specifies styled letters that are to be implemented within a font style.
Often it isn't clear what to do.

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The script glyphs and planck constants in Letterlike Symbols (U+2100-214F) in the non-italic fonts do not fit the design characteristic of the font. The glyphs in non-italic fonts should be strighten up.

        ? I agree that the script glyphs are very slanted, even for handwriting.
        Where did they come from?
        Maybe there is a less slanty script version.
        The Planck glyphs are arguable.

The bold versions of script and black-letter glyphs (U+2100-214F) have different stroke paths from the non-bold counterparts. The bug does not exist in other font families.

        ? The script and blackletter glyphs in bold are from different faces than the non-bold counterparts.  I don't see this as necessarily a bad thing.  Not all faces ought to have a bold version.
        And then there is the general question of how to handle different face designs within a single face of a font...
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