(Page10)「月が綺麗ですね(tsuki ga kirei desune)」=「The moon is beautiful」 The Japanese novelist Natsume Soseki has an anecdote that he translated "I love you" as "The moon is beautiful" when he was a lecturer in English for students. Mokou did not know about that, and she said that as a topic of weather[*]. But Kaguya knows about it, so she blushed.
[*](Title) "Tenki no Hanashi" = "A topic of weather"
I'm sorry I have no power to write good English nor the ability to make an English version.