This song is the exact reason why I have a problem with the following:
1) English VAs. Some aren't terrible, but Christina Vee is one of the most earbleed-inducing ones I've had to deal with. In all honestly, she belongs on youtube doing bad fandubs because that's what I feel like I'm listening to. Her voice just feels too underwhelming for what she voices. She sounds like the right age group, but it just feels a bit too forced. I'll give her credit for what she does, but all I can say is I wish someone else did it.
2) The English language / lack of accents in the language. It really shows in this song how dissonant and distorted the vocals of the English language are in the more natural accent (I suppose I sound like an ass to any other English-native country, but I will go on the assumption it isn't "too" different vocally between the US and any other English-natvie country.).
A good amount of European languages and virtually all Asian langauges have really good accent harmonics, even in English (I'll go ahead and say it's a hit or miss, on the far ends of the spectrum). It's hard to explain beyond that. Just compare some good English songs you listen to with other languages and take note of the words and accents, there tends to be a notable difference, at least to me.
Maybe my #2 was a bit biased, I generally take a lot of concern for my vocal harmonics. If case #1 didn't exist, I probably would have said nothing besides saying the generic "leave it in Japanese please".