i think it's possible to see the cognitive functions as physical processes, actual brain pathways. nowadays it's more interesting, in my mind, to re-interpret the cognitive functions in a cognitive context. cognitive psychology and cognitive science, during jung's time, didn't exist. now they do, and cogsci in particular, is home to the most interesting research into intelligence, the mind, etc. it's the best academic site with the most interesting intersections.
thinking of the cognitive functions as brain pathways leads in a different direction than thinking about them as an ego complex
. where you have like aerobic and anaerobic mode, where you flip a switch and live in your own shadow consciousness, where the orientation of the functions reverses direction completely. if that were the case, it would seem like some strange version of schizophrenia, bc nothing would be mapped out or learned in those brain pathways, and no instincts would be developed, and you would have no way of framing experience, finding meaning, or sorting information.