I have to say, Mihari is really cute on this page, especially panel 1 and 5.

"She's really cute, athletic, has top grades and it's the most popular girl in the school".

Have the japs realized how cliche this is? I'm not even sure they are using it to make fun of it or if they keep using it unironically.

Probably because this sort of thing is "ideal" in their culture, and to top it off it's supposed to be the elder sibling who is "best". It's almost certainly being invoked deliberately because him being worse than her in in academics and sports is something that, culturally, he probably would feel shame over.

I'm inclined to agree with Garrus. Also usually these days, the "Perfect" older sibling isn't ment to be a main character anyway and instead, the main character is the younger "idiot" sibling who looks up to the Perfect one. I've seen this kinda trope invoked in animes since as far back as the early 2000s.

Said "Perfect" characters really only show up 1 or 2 episodes an arc anyway just to remind you that the main character is going through their growth phase.