As someone whose job involves making admissions decisions for graduate students in a STEM field, I can tell you I 100% do not care about a student’s high-school AP Research credit or the project it entailed. It happened in high school. It’s in the past.
The credit portion, as I mentioned, is irrelevant. It sounds like your daughter had a great experience, but the research portion is simply too far in the past. The level of contribution provided by a high-school student is going to be lower than an undergraduate on the same project, which is in turn lower than a graduate student. The real value in such an experience would be using the experience to confirm her interest in research and leveraging that to get into a good research situation as an undergraduate where she can show her potential at a higher level.
I am sure she is, but so is every other applicant.
In research, as much can be learned from a failed experiment as from a successful one. Whether the results were favorable to the hypothesis or not is irrelevant to the quality of the research performed.