Yo, thanks for the TL! I gotta ask; is that how he talks? Stiff Japanese?
In the original Japanese, Arthur talks with a lot of redundancies, technically correct but unorthodox sentence structures, and mismatched tones, making his speech sound incredibly odd. It's not that he's stiff or formal, like Tanimura would be, it's just really odd.
Parsing his sentences takes a bit of work, but the oddness of his speech is meant to be comedic. I've taken inspiration from Fawful, of the Mario and Luigi series.