Changing MathJax fonts after loading
Should I be able to change fonts after MathJax has loaded?
The font data is loaded when the HTML-CSS output jax is initialized, and you currently can't force that to be reloaded without reloading the page. One of the plans for the future is to allow MathJax to use more than one font set at a time (something like the MathJax TeX fonts first, and if a character isn't found there, try the STIX fonts). At that time, I expect to make font selection more dynamic, but that is in the future.