Honestly, I majored more in Japanese than English. Can you please point out other "very awkward English" points? I'll fix them right away. Btw, there are not that many proofreaders in our group, so we would be happy to accept you as a proofreader. (join the Discord group and then contact KDT)
Also, on page 23, the Japanese version did use the "secret talk (内緒話)" word instead of just "listen in on" (which is a new phrase in my dictionary, thanks!).
(Update: The chapter has been edited)
I'm sorry to say that I wouldn't have the time to work as a proofreader, so I'd likely be more a hindrance to you than a help.
About the secret talk: this is probably just a matter of opinion, but since the context is about the mother using a wiretap to listen to spies, she would obviously be interested in secret talk, and not small talk, so there should be no reason to specify that.
As for examples of awkward English, page 1 has: "Gradually, I also received more detailed guidance" would flow better as: "I also gradually received more detailed guidance", though this is a fairly minor example.
A much better example would be (also page 1): "Good job, myself", which you never hear in English in real life. A better expression would be: "I did pretty well, if I may say so myself" I know it's not quite the same, but translation is about getting the meaning across, rather than just the words. In the Japanese, she's praising herself for a job well done. My suggestion sounds like she's bragging, but it's fairly close to the original meaning.
Then there's page 2: "Particularly, it's okaa-sama" It would flow much better as: "The biggest problem is okaa-sama" or something similar to that. Alternatively, "especially okaa-sama" could work too.
I could write more, but I'm already running out of time for today. Sorry.