Congrats on your acceptance. I agree with the other posters: do not report that you were accepted to Cornell. Merely applying RD instead of ED doesn’t suggest they are second choice as lots of students have to apply RD in order to compare aid offers. However listing the Cornell acceptance for sure confirms their second choice status. Also, you risk AOs concluding that, if you were a fit for Cornell, you aren’t a fit for their T10 school, as they have a different vibe and are looking for different qualities in their students.