Nanase being pretty indifferent about this sort of thing shouldn't be terribly surprising. She, undoubtedly, the one telling Elliot what to name his attacks, then wanted to date him.
What, however, is the "correct" opinion to have here, a hypothetical person asks? Heck if I know. Here's some characters and how they feel about things. Hypothetical person will have to reach their own conclusions.
I will, however, attempt to list the following things in a list-like fashion to the best of my ability / knowledge, and trying not to speak for anyone else. These are in answer to various "what's the issue" questions I got after the last comic:
- Referring to one's self with honorifics can be seen as anything from rude, to childish, to just sort of weird. They're supposed to be for referencing other people, and an indication of relative status and/or familiarity (which is why just leaving them in translations to English can be more sensible than trying to find some other way to get those things across).
Hanma calling herself -chan isn't that bad, and could potentially be seen by some as endearing (if possibly childish), but calling herself -san and -sama probably wouldn't go over well in general.
- I don't think it's that difficult to imagine how someone might not like people running around adding Japanese honorifics to names just because they like anime (particularly if used incorrectly / haphazardly).
- There's potential to rub people the wrong way by using words from / speaking a language poorly, particularly in a case of someone not putting in the effort to learn proper grammar and pronunciation.
( EDIT - A reasonable person considers someone's circumstances and why they might not speak a language particularly well, as it's often not a simple matter of effort and/or desire. )
Worth noting is that Hanma took offense to her Japanese being described as "poorly spoken", and it's safe to assume she's not doing so intentionally. Nonetheless, it's not difficult to see how this could be annoying, and why she could get called out on it.
An example of people finding such a thing annoying / problematic is how, in the TV show Firefly, Mandarin Chinese was often spoken (seemingly at random), and I've been told it wasn't done well. I consider it understandable to consider the lack of effort to get it right as disrespectful.
Also a point of irritation was that there mysteriously weren't a lot of characters of Chinese ancestry around in spite of the lore reasons why Mandarin kept getting spoken, but I'm focusing on words used and stuff. Still, what the flip?
The story in the comic itself is going to be moving on right quick to more board game-ish things, though the commentary might return to this subject. I did want to characterize Hanma a bit, however, and to possibly address that nearby 10,000 lbs... wait, is that big for an elephant? I feel like I've asked this before. Whatever. There was an elephant around. I wanted to address it.