mod_proxy_cluster needs a module that would provide a comprehensive command & control visualization of events going on within the balancer and with worker nodes. The visualization would also serve as a demonstration for presentation purposes (to replace current SWING app from ~2009-ish).
The new module would most likely work with https://d3js.org/ and generate an SVG/JS page on a new added httpd handler. For this new module to work, we need JSON data from mod_cluster manager (currently spits out only HTML/text/XML).
I find the Wildfly style of Undertow mod_cluster proxy filter CLI output the most suitable: