Earlier quoted context omitted.
A great way to get help is to ask for it. I'd imagine the ffmpeg community would be a lot more open to helping you if you didn't start off by saying their tool is broken, though
It is clearly broken and very-very-very deeply so. On organizational level. Quote Gemini: This error is the "smoking gun." It confirms that no matter how we quote the command, your shell is treating the comma as a separator for the FFmpeg command itself rather than a character inside the filter.
Your reliance on the random word generator is making the point of OP.