There are still plenty of technical and scientific uses of the word in various forms, including retard, retarded, retardant, and retardation. One that’s in common use outside the sciences is “flame retardant”.

Technical usage, where the word is describing a quantity, process, or function include: retarded time, retarded position, retardation time, regarded coordinates, retarded Green’s function, retarded potential, retarded acceleration, and retarded ignition.

In all these cases, it’s used to refer to something whose progress is delayed or impeded in some way, which is the original meaning of the word “retard”, that also ended up being used in medicine and psychology and becoming a slur in those contexts.

So the correct answer to my original question is either “no” or “it depends”, with the latter requiring some qualifying criteria.