Hi @tempo .
I am not sure if wpForo can add a "math editor" or an "equation editor" onto the built in "text editor" for "replies" or "posts".
These posts are basically "forms" and surely there is a way to add anything to "forms" but it will be a highly customized one that you might need to hire a developer for.
If you are just needing to publish specific formulas or a few formulas onto a post, what I see "instructors" or "trainers" do is they create (basically draw or type) these formulas in a software like "Paint" and then save it as jpg file, and then attach the image / jpg file, to their posts. 🙂
As Chris says, for direct editing you would need to integrate something like the Tinymce Wiris plugin into the core WP functions and then run a filter through theme functions to add the relevant buttons to the WPForo editor. Such would be the realm of a developer.
If you merely want to properly render equations for display purposes then the MathJax-LaTex plugin does work in WPForo.
@verek , thank you for sharing that. I learned something new. We use old school, but if a new plugin is out there to make life easier for formulas, we can test drive it too! I appreciate the tip! 🙂 All the best!