She was a grad student, she just wasn't a grad student in physics or cosmology. She was a political science grad student, who ended up working under Dr Foster because apparently she was the only one crazy enough to apply for her internship. And Jane was desperate enough for help that she'd accept anyone.
Thing is, while this wouldn't make for Darcy being a good scientist or techie, a solid foundation in the social sciences combined with a strong head on her shoulders ( see also: her surviving being near to two different Asgardian-level incidents )? Would probably be a good basis for working in dealing with Weird Crap. Let the techies figure out "what", she can work on the problem of "who" and "why" and "what do I have to say to keep you from blowing up Topeka".