Yes and the official "localization" is wrong to do so too. And this is literally a comic, sounding "too comic booky" is not a reason to not translate accurately. And regardless, there are other accurate options, one of which I gave, that you chose to ignore in order to make a bad point.
I'm interested in continuing the discussion, so let's have a friendly chat on the topic, shall we?
Of course, if your opinion is not up for debate, that's fine too. ;m;
Also, I wrote this while feeling a little muddled, so I realize not everything may make sense. XD
My understanding is that localization is simply meant to make the product appealing and culturally acceptable for a new target audience. It often comes with the unfortunate side effect of significantly, and sometimes questionably, altered context ("Jelly donuts" in Pokemon or Calamity Gannon's "motive" in Breath of the Wild). While I can see how such changes in context could be considered "wrong", I find it difficult to apply the same thought process to translation alone.
I believe translation is very much an art, especially if it is between such different languages as Japanese and English. I don't deny poor translations that are difficult to read and understand exist, but that's different from stylistic choices. I got used to reading scanlations that kept the original place names, titles, etc. and appreciate them because of the extra context they give. I generally dislike it when "Koji-san" is replaced with "Mr. Koji" or the like, because it eliminates some of the finer relationship details that exist in Japanese culture. Similarly, I have a hard time understanding why some terms are translated when English has no good substitute, or the loan word is already well known.
In this case, I believe the use of "Ni no Kuni" as a place name was a stylistic choice. In context, it is being used to identify a location no differently than using the names Hokkaido or Sapporo to identify locations. It does not change the context of what's being said. If anything, it remains consistent with the other elements of the manga. Would translating it fully to "The Second County" or "Earth II" make it any more understandable? Would such a change still retain the original feel of the work? Personally, I don't see that.
What I understood from
Shinjinotikari17's explanation, is that fully translating the name would not fit the story/sound awkward, would eliminate some of the Japanese identity, and break consistency with the rest of the series. (Please correct me if I'm wrong!)
TL;DR: Using "Ni no Kuni" as a place name fits within the context of the work and helps it retain some of its Japanese identity while remaining appealing and understandable to most of the target Western audience. Fully translating it could change the feel of the work and may dissociate it significantly from its roots and the rest of the officially translated materials.