This amazing plug-in is now working on our site. As advertised, it is a Computer Algebra System which can "understand" mathematical expressions can figure out whether two expressions are equivalent!
Many thanks to Christoph Sangwin to personally testing our installation. And to Michael Kallweit for entering sample content directly on our site!
BTW, for German speakers, there is excellent documentation created by Michael and his team in the form of OER on https://open.ruhr-uni-bochum.de/lernangebot/video-tutorials-stack and Videos on https://www.youtube.com/channel/UCVZlSGGitFm_rhP2cRftcLw.