Color & bitmap fonts are the future of type, but the future is full of technical hiccups ;) If you ever tried to export PDFs with OpenType-SVG vector or bitmap fonts, you might have encountered several issues, like missing glyphs or fading colors, because they are:
Unsupported by current PDF format specifications
RGB-only & not compliant with PDF/X-4 due to the lack of color profile (there is currently no way to embed CMYK glyphs)
So while Illustrator officially supports such color fonts since CC 2018 and InDesign since CC 2019, you may have to circumvent such limitations by turning glyphs into outlines/images - and sometimes fight other bugs - to generate functional PDFs.
Update: Illustrator & InDesign 2020 seem to automatically generate PDFs that are better suited for OpenType-SVG fonts, as they apparently don't require the glyph outlining preset detailed below.
Take this example featuring an OpenType-SVG bitmap font in an InDesign document:
Exporting it with the default PDF settings will lead to a PDF file where all glyphs are replaced by... the background photo 😵:
To fix it (this only works with & above CC 2019, not older versions) you should go to Edit > Transparency Flattener Presets, create a new setting and check Convert All Text to Outlines (our understanding of this option is that all glyphs will be turned into their core component - vector outlines for standard fonts, images for bitmap fonts). Save this preset with a bespoke name and press OK.
Then go to File > Export to generate a PDF, from General settings pick Compatibility > Acrobat 4 (PDF 1.3):
⚠️ If you get pixelated results when exporting the PDF, you can also boost the output resolution, say from 300 dpi to 600 dpi, and use a lower compression:
Then head to the Advanced panel and under Transparency Flattener pick the preset you just created, and export your file:
Ok, now let's check the PDF. If you are lucky enough the glyphs will look ok... well, unless they don't:
Apparently, semi-opaque areas can look funny in PDFs if the background image is also textured. Turns out these visual artefacts on screen are not visible at all when printing the PDF:
😅The hard-learned lesson is that you should always Convert to Outlines for PDF support and try the entire production chain before using OpenType-SVG fonts - specially when exporting such files for third-party use (BTW your local print shop will definitely enjoy the technicality of your cool color font projects).
PS: special thanks to Andone Simona Alina for accepting to showcase her project made during a workshop at the Swiss art school ECAL.