Depending on just how many interns we're talking about, I wonder if taking notes in brief one-on-one interviews might be practical. You'd get better feedback from focused conversations than you're likely to see from form responses since it's such an open-ended field.
Two now who are about to go back to school and another replacing them. Total new-ish team members is 4-5 so interviews would be feasible.
Any thoughts on resources for asking questions?
"You/your colleagues mentioned you want/would have wanted more training with Postgres. Could you go into more detail on what you've struggled with, what concepts or aspects of working with Postgres you've found unintuitive, and where you think a slightly-more-formal crash course would have helped you?"
And then you let them talk, ask followup questions to get as much detail as you can, write it down, and see what patterns emerge.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.