As I am sure you have concluded by now, your challenge is how you discuss with a group of evaluators how you elect to spend your time. Each applicant has 24 hours in a day and they all choose to spend that precious time differently.
You will need to explain your time in essays and in interviews. You have not told us the complete picture here, but if you go to school and privately play piano --- an nothing more, you are disadvantaged in comparison to your peer group. If you are 100% focused on academics - the test scores, level of difficulty of courses taken, and the final report card will substantiate and validate how and why you spent the time in that area. Service Academies are looking for multi-dimensional applicants. Hence the whole candidate score approach. In general, a singularly focused applicant will have a difficult time applying unless their performance in this one arena is exceptional.
You have described a hobby that consumes some of your time. This is not a bad thing, but it is difficult to convey in 10 words or less to someone who has never met you. Resume bullet statements like this have historically equated to fluff and do not tend to move the needle to progress your application. Some students enjoy woodworking, or skiing, or hiking - but it simply speaks to an added dimension about you.
My hope is that there is more to your extracurricular resume to provide a more complete picture to a committee as to how you elect to spend your time.
I am unsure if you even include this on a resume unless it is part of a broader hobbies section. It is a nice response to a panel question about "Tell us about what you enjoy doing outside of school and working on your college applications..."
If you want to turn this into something to talk about, you have time to craft the narrative. As
@A1Janitor suggested, you could teach lessons to an underserved community or group like Boys and Girls club. You could volunteer to play at a retirement home. You could play in the lobby of a Children's Hospital. You have a tremendous talent - be giving with it and as a result, you then have a great story to tell about serving others.
Weave it into a talk that includes the Air Force's 3 Core Values -
1) Integrity First
2) Service Before Self
3) Excellence in All You Do
Change the narrative from "I enjoy playing piano" to "Gifted piano player who regularly performs at Children's Hospital volunteering more than 150 service hours to spread joy to sick children in my community."