Someone probably said this (I am sorry for not reading everything). But I think it is not related to the style you are writing it in, but more the origin of your characters. If they are japanese, or inspired by japanese people/culture, it would be normal for them to use chan/san/kun/etc. Or if they are otakus/weeaboos/anime fans/whatever.
Like, The characters from Hearts of Keol are korean/korean inspired and "use" things like "oppa", "sunbae" to call each other.
When you translate you can use like "sr" "mistress", etc, but somethings are hard to equate, like "noona", that's like "older sister" for boys, very specific. I think it that's what your character would be using in their language, it is cooler to not translate, just use "chan".
But if your character isn't japanese, and/or he isn't polite enough, or don't know how to "behaviour", makes more sense if you use different honorifics, or don't use them at all.
A tip for native portuguese speaker characters: we give gender toto stuff when we speak a different language (?) I am saying it because I just did it xD When I refereed to the character as a "he", is is because in portuguese, the word "character" is male, so we use male pronouns when using the generic word "character".
I think it is REALLY insteresting when you research to make characters speak in the way people from the country he is from speaks. I mean, of course it is hard to check the way of talking from every single language you don't know, but it is interesting to add stuff like that. Like... Brazilians rarely use honorifics, just in workplaces, and not always.
So if it is a brazilian talking in japanese with japanese people, chances they are going to drop the "kun" or "chan" or "whatever" are not low. Portuguese (from Portugal) people use A LOT of bad language... And goes on.