Using alternate language glyphs in conversion

[barbiedolphin]

Some fonts have alternate glyphs for the same character(s). For example, the Cormorant fonts have extra glyphs for the Bulgarian stylistic variation of Cyrillic.

However, when converting to EPUB or PDF (from EPUB, usually), Calibre just uses its' base Cyrillic glyphs (which are the more common "Russian" variation of Cyrillic).

When converting to EPUB, I've tried setting font-language-override to Bulgarian in the CSS stylesheet, doesn't work:

<style>
font-language-override: "BGR"
</style>

(Furthermore, is it supposed to be "BGR" or "BG"? There's no documentation anywhere, so go figure.)

There's a way to select a unicode-range, but this seems even harder. But Fontforge shows that Cormorant Garamond Semibold has most of the Bulgarian glyphs inbetween "в" (66160 0x10270 U+???? "uni0432.loclBGR") and "ю" (66214 0x102a6 U+???? "uni044E.ss10")

And all of this doesn't help if I have to convert to PDF, either.

[Doitsu]

Calibre supports stylistic sets, which you can use to select alternate glyphs.

Spoiler:

@font-face {
  font-family: 'Cormorant';
  font-weight: normal;
  font-style: normal;
  src: url(../Fonts/Cormorant-Regular.ttf);
}

body {
  font-family: 'Cormorant';
}

.ss10 {
  -moz-font-feature-settings: "ss10";
  -webkit-font-feature-settings: "ss10";
  font-feature-settings: "ss10";
}

You might find the OpenType Tester website useful for experimenting with OpenType features.