It's more of manual process, and I'm not sure this is going to be very easy; it's more about searching to find the appropriate symbol in that menu. Some of those equations are very long. With MathJax, we can write the code very quickly and it is interpreted appropriately.
One of the groups who uses this service would like to have the ability to occasionally write in a math equation. This is something we've historically been able to do using a javascript called MathJax. Here's a link about Mathjax: https://docs.mathjax.org/en/v1.1-latest/mathjax.html Here's instructions on how to add it to wordpress: https://docs.mathjax.org/en/v1.1-latest/platforms/wordpress.html It seems to be something you can either add to a header.php file or use a plugin to accomplish. I think this would be useful to any STEM website.
We use Mathjax to write equations in titles and abstracts of presentations in our wiki, as in this example: https://hilbert.math.wisc.edu/wiki/index.php/Probability_Seminar
Name: Sara Nagreen
Email: nagreen@math.wisc.edu
Website: https://mxm.math.wisc.edu