The key points include grammar and syntax. Since light novels can be quite diverse in their writing styles, the translator needs to be well - versed in both the source and target languages' grammar and syntax rules. Also, the use of appropriate vocabulary. Using words that are too archaic or too modern can break the mood of the light novel. And finally, consistency throughout the translation. If a term is translated one way at the start, it should be translated the same way throughout.
Accuracy in character names is important in fantranslation of light novels. If the names are not translated correctly, it can be really confusing for the readers. Then, the flow of the language. It should be smooth so that the readers can enjoy reading without getting stuck on odd - sounding phrases. And of course, staying true to the original author's intention. This means not adding or changing things too much just to make it easier to translate.