Thanks for the inputs! I am glad to hear that my basic idea might not be very flawed as it often is. I feel better for dd just wanting to improve m*th cooking skill and learn stats at community college instead of filling up her sorely lacking EC. Her rather decent early visual art achievement might go waste by not adding anything during high school, which will leave only dull academics on her application even without some academic Olympiad participation.
Collecting more college courses won’t help much in admission since she already has enough, but the knowledge will help her getting better ug grade later, and might even land a research opportunity for developing the elusive blue m*th in college lab, even though she won’t have time for doing it on her own for some high school research competitions. Beside, what good would unwanted volunteer do for character building, or everyone-gets-some,1-hour-per-week club’s co-treasury position for actual leadership experience? Adcoms are supposed to be able to see the shallowness anyway right?