I have an FSE-related question

• I'm trying to add a font to the 2023 theme but it's not showing in Gutenberg editor.
• In theme.json, in the "settings.typography.fontFamilies" section, I added the following fontFamily definition:

{
    "fontFamily": "Sarabun, sans-serif",
    "name": "Sarabun",
    "slug": "sarabun"
},

I realize that this doesn't import the actual font definition files (...woff2), but I think it should at least show "Sarabun" as an option in gutenberg when I edit a Paragraph block and select the "Typography > Font" dropdown.

Note - this does work when I do these steps on the 2022 theme.

QUESTION - Does anyone know why the font (eg "Sarabun") wouldn't be showing?