I hate this chapter. This isn't misunderstanding. It's bad writing.
Unless there are some nuances to the Japanese language that we are losing in translation, then this is the dumbest and most infuriating chapters so far.
From what I have gleaned over time -
Japanese as a language relies a fair bit on context in how it's grammatically structured, because certain aspects of grammar that you would find in languages like English don't exist.
If I am correct - then terms like "performance" on p.6 are being referred to by both Ayase and Kaori in different contexts, but neither are outright stating those, simply assuming that
their particular version is the correct one for the conversation. Because it's inferred and not outright stated--due to how Japanese works grammatically, it's literally absent unless specifically worked into the dialogue by further clarification on the speaker's part--the misunderstanding arises.
I only know enough to know that I need to read & study a
lot more to get a true grasp of it, but effectively it
is lost in translation, as far as the specific nuance at play--which is why the TL put those specific words in parentheses--those are for English speakers to see what inference is being left out of the actual dialogue between them, so that the joke still lands because translated (more) literally, it wouldn't be as clear that Ayase & Kaori are using the same terms, but speaking to wildly different contextual subject matter.
Someone once told me it's akin to a form of linguistic word play, but happening entirely "accidentally", and is a result of how Japanese as a language is structured, rather than a purposeful effort on the part of the speakers to obfuscate their intent. It's not 1:1, but assuming they were correct, it gets the idea across, for me at least.
Kinda like the "Who's On First" Skit, I guess.
The question from there is whether the reader (Japanese, English-speaking, or otherwise) finds it funny, but that's what I assume the mechanics at play consist of, at least.