He's speaking Japanese in the raw, so it's probably very simple and formal enough that an American with rudimentary Japanese knowledge can understand. He's saying he wishes he could speak English because it would have been easier for Mr. Foreigner than dumbed down Japanese.
That's fair. I trust this author not to shit the bed by falling into the worst genre tropes. It's not the only way to avoid the axe... There's still the option of good writing, right? Please?
I've been trying to make "neh?" happen ever since I read it in Ender's Shadow. It's the perfect word American English is missing - neh? Isn't that true? Isn't that so, neh?