maybe they try to translate everything word per word instead of making it sound like conversational english
example, in tagalog, "mabait ka na tao" is translated to "you are a good person" but if it was translated word per word it would be "good you are person"
the japanese are also very formal and use a lot of honorifics which might be lost in translation. since you live in japan, i'm sure you know that best :)
Actually, I feel that it`s the translator`s style (?), especially since I`m Japanese. I`ve had the chance to read the Japanese version of the manga, but I doubt any of those lines would translate to phrases like "i tell you". Much less so much of them. Besides, if Japanese was that unique in dialogue, more manga would be similar in translation, but as far as I know, this is the only manga with this unique translating style.
BTW, I used to live in Philippines until last year (for 19 years). It was a little nostalgic seeing a tagalog phrase(＾◇＾)
i know i should be glad enough that someone actually puts all their efforts in translating, but recently I just can`t get over the awful lot of lines that say "i must say", "I tell you",
and "i assure you" after a dialogue! I love the manga though... just that i get too bothered with those lines...