Given that we have no context, I think "University Professional" or "University Graduate" is closer to the meaning in Spanish. I wouldn't use "University Staff" as William suggests, because that may very well include the University's security staff or even custodian/janitorial service staff, not necessarily a professional.

Regarding "planta provisional", in many Latin American countries there are two options: "planta permanente" (permanent) and "planta provisional" (provisional/temporary). The latter usually means that the position that needs to be filled is temporary, not long-term. It has nothing to do with a tenure-track, quite the opposite.

Another option could be "University Professional for temporary/provisional position" if we are talking about job application. But, again, it depends on the context.

I hope this was helpful! :)

Another word which describes temporary members of staff is 'interim'. There's an interim agreement which is belonging to, or serving during, for instance, a piece of work which takes place during an intermediate interval of time.