観戦、グルーヴコースター / Grooving on Groove Coaster
はぁっ！
これで決まり……でござる！
Hyah! With this final trick...this competition is ours!
This girl is Ran, who uses the archaic “-degozaru” ninja / samurai -like manner of speech. In fan manga translations, this is so irreplaceable that they just literally add “degozaru” to each English sentence. But in official games like this, it had to go completely. Still, “this competition is ours” is a decent replacement, but not immediately quirky like “degozaru”.
うん！
それに……一番のお目当ての子は、次のプレイヤーだからね。
Indeed! And this next Groover is one everyone's excited about.
さて！ 続いてプレイするのは昨年の全中王者！
孤高の天才！ 響華女学院の氷芽川アリア選手です！
All right! Up next, we have last year's national middle school champion—the Solitary Prodigy! Representing Kyoka Girls' High School, make some noise for Aria Himekawa!
Like in the prologue, Linka uses both zenchuousha 全中王者 and kokou no tensai 孤高の天才. The first one sounds cooler and more like a moniker than “national middle school champion”.
全中ってことは、中学生の大会ですよね？
俺とタメで一番すごい選手ってことじゃないですか！
So she was the champ of a tournament for middle schoolers? I guess that makes her the most amazing player among those my age, huh?
Kakeru tries to decipher the 全中 part of the 全中王者 moniker, working out that it is the 中 of middle school 中学生, so it only works in Japanese. In English it is already deciphered, and Kakeru just repeats what Linka says.
奏でる、グルーヴコースター！
Resound, Groove Coaster!
Wow, I like the English translation of her hype sentence here.
流れるような美しい演技です！
さすが孤高の天才！ 高校でも進化を遂げているようです！
Such a smooth, graceful performance! It's no wonder they call her a prodigy! Even in high school, she seems to be taking her craft to a new level!
In Japanese, Linka continues to glaze her with the exact moniker kokou no tensai 孤高の天才, “Solitary Prodigy”, and not just the “prodigy” that the English one used.
（すげぇ丁寧だったし、優雅！
っていうか、芸術的？ 全然目が離せねえ）
(Her performance had such finesse! Or should I call it elegance? Artistic flair? Whatever it was, I couldn't take my eyes off it.)
（俺もあんなすげー演技できんのかな……）
(Can I really pull off something as amazing as that?)
Kakeru repeated “sukeiー” for both but it can’t be spammed the same way in English.