Unfortunately that is not possible from what I know.
This question has come up before, over here and here, in a slightly different form about calling generated images, after Image Processing Methods.
So I cannot think of a way that you could add logic to call generated CSS or JS resources from the templates with existing methods.
Perhaps we could make a request for a new method to check whether a Resource is already generated and present in Hugo’s Cache.
Something like resource.Cached would make possible conditions like:
{{ with $css.Cached }}
{{ .Permalink }}
{{ else }}
<--- "process yourself logic" --->
{{ end }}