they can absolutely see uranium. It ionizes and thus get separated like many other things https://pmc.ncbi.nlm.nih.gov/articles/PMC7470433/

Calutrons are using the same principle of separating ions by their mass/charge ratio, just in a preparative scale (you want to collect what is separated) rather than analytical (you just want to know how much of what).

sounds like this is similar to doing basic paper chromatography and cutting out the strip with scissors just to get the desired substance, spectrometry as means to produce the material rather than means to analyze

Mass spec is about separating things by mass... exactly what enrichment requires.

A mass spec used as an instrument measures the components of a substance, this is just the same concept for actual separation of components not just to look at them