The thing is not to discuss whether acting is an sport depending on what does the activity require from the performer, but what the series is actually trying to reflect: the competition that acting can actually become or the personality, feelings, evolution, and overall drama of a main character while they try to achieve something. And even if Act-Age basically shows both, I really consider it's way balanced to the second option, which is why I can't just force Act-Age in a 'Sport Category' and reduce everything the series is in just a competition between actors and actresses (which actually not a single Sport series does because character development is way too relevant in all of these series, but you get what I mean, it's just like putting series in a balance and determining which is the most distinguished element in the series).
Genres or categories are not one and only, they're pretty flexible and even arcs sometimes shift the whole genre of a series, but analyzing the whole, I don't think Sport is the best category to fit Act-Age in.