As far as I can see from the browser calls, the JS code from the initializer JS is side-loaded through discourse-math.js, via eval() (on every page open), which clearly suggests that some server side component is processing and caching that JS code from the initializer (which is the one I’m changing), and hence it’s that particular server-side cacher that needs to be triggered into re-caching it … which doesn’t happen if the plugin is symlinked but does when it’s copied.
I’m not familiar (and I didn’t want to get familiar at this time due to lack of time) with the Discourse toolchain … hence my reverse-engineering and questions.