No, she's written to excel at everything she tries, the first time she tries it.
- asks Keisuke for help with a test; Keisuke studies with her, gets a 95; Kusunoki gets a 100.
- during dodgeball, Big Kid gets a whole team out, then Kusunoki solos him with ease (2v1-ing Hebikawa at the same time, mind)
- volleyball at the beach; 2v2, and Kusunoki & partner aren't even winded after trouncing Keisuke & partner, who're left gasping on the ground
- gets picked as lead for play, never done it before, has standout performance with a bit of improv even
- can't make friends and is awkward, whole reason for needing Keisuke's help with 'debut'; first time at café with three girls, makes friends with each within a couple lines of dialogue, winning them over entirely.
- and, during flashback when she meets Otobe, it's when she's a goalie during a game of football, and Otobe gets made at the boys for "going easy on Kusunoki" because as an elementary schooler Kusunoki's athletic enough to block every goal attempt.
Sure, she appears awkward, but other than some as-yet-unexplained backstory from elementary school, she has never once failed or even stumbled at anything she's tried, surpassing others even when they put in the equivalent work & effort.
That sort of characterization is why people call her 'perfect' and why her character also is deemed less interesting than someone like Hebikawa that has actual faults (not 'oh no I'm so awkward').
Sure, Kusunoki is a much
kinder character, but she is the far more flat, dynamically, of the two.