Many people's understanding of all-round development is: I know this, I know that, my piano is Grade 9, and my art is very good.
This understanding is wrong.
The synonym of "comprehensive development" is "one specialty and many functions". There are many people who can do everything, but it is difficult to find a prominent stunt, which many universities want to find. There are many people with Grade 9 pianos, but few people have won international prizes. Even the latter, for the limited admission places in universities, can't be said to have entered the safe. After all, every university should recruit students with corresponding abilities according to its own professional courses.
Back to your question, you said that you studied 12 Peking Opera 1 1 year calligraphy. This is just data. In the interview with HKU, what you need to show is what kind of life experience you have gained even if you are not internationally recognized. Whether you have a deeper understanding of yourself through persistent dream pursuit, whether you have cultivated a maverick character, and whether you have new inspiration for modern life under the influence of traditional art, these deep sublimation should be what HKU interviewers are looking for.
I wish you progress in your study.