It seems Font.renderGlyph() is not implemented for html5 target.
Sorry this is not implemented outside of native platforms!
I think it should be possible to wire this up fairly easily using canvas:
https://www.w3schools.com/graphics/canvas_text.asp
Embedded fonts are included on HTML5 builds using the name of the font (not the file name – the actual name) as the name in CSS, like “Arial Regular”