No, I don’t interview for Princeton. Looking at comments by persons who do interview at Princeton and applicants who have had interviews, a common theme seems to be talking about passions and elaborating on activities beyond what is listed in the application questions. I think it’s likely that the research would come up as a topic of discussion during the interview.
The college I interview for doesn’t have a specific set of rules about research, such as try to evaluate research in more detail. Instead I am instructed to evaluate applicants on a group of characteristics that are extremely similar to what the website says they are looking for in applicants. For each criteria, I write a summary about how the applicant meets that criteria and give a numerical rating. The research sounds like an interesting and meaningful activity that would be a good example of multiple evaluation criteria, so if I were interviewing, I’d be likely to ask questions and try to get the applicant to go in to more detail.
Princeton as well as other HYPSM… colleges make it easy to switch between majors, so a lot of students do switch majors. However, I’d expect many of these switches are to similar fields. For example, a prospective EE major who has never taken an EE course during HS might switch to a CS major at some point during college. The same Princeton quote that mentions they high major change rate also mentions, “The only exception is for students who indicate that they will be applying to the bachelor’s program in the arts or in science and engineering. Within those two programs, they are encouraged to explore the academic offerings until they declare their majors after either their freshman year in science and engineering or their sophomore year in the bachelor of arts program.” As such, while Princeton may not be as big on being passionate about their prospective field as certain other colleges, they still want students who appear to be highly capable in their prospective field of study and likely to stay in the general engineering/science area. And I’d expect they still would be interested in hearing more about the research. The essay/statements in my previous posts seem to direct such elaboration, and I think it would also be likely to come up during the interview. Several comments on the Princeton admissions website hint at wanting detail about such activities.