I think if you use the default export, it should work as expected (i.e. without needing to inject the router service, or manually pass in a reference to it)
import routeAction from "discourse/helpers/route-action";
(not sure why there is also an internal function exported as routeAction… pretty confusing! Let’s fix that)
Although I would say… in general we are trying to move towards ‘closure actions’ like {{on "click" this.someFunction}} rather than string-based things like {{action "blah"}} or {{routeAction "blah"}}.