I know what I'm about to say is probably common sense to a lot of people but it also isn't to others unfortunately. Translation is taking the original words and converting them to the new intended language (like google translate), leaving it in this state is referred to as transliteration quite often because it is TOO literally/directly translated (the fact that some people like this + a whole swathe of translator notes to explain things is a different matter entirely). Localization is the process in which you take the newly translated text and make it actually make grammatical and literal sense in the new language.
The art of it comes in knowing when to deviate and how much in order to carry the meaning of the sentence without requiring explanation. A good example of this is a much earlier chapter of Tomo where Mizusu told Carol to listen to her and one translation just went with a more literal word accurate translation while another knew that the exact words used were rude and condescending within the context and so deviated to something that, while less word accurate, conveyed this without translator notes or further explanation. Retaining word accuracy can be counter productive to retaining the original meaning due to various differences within the language structure itself and the culture of those speaking it. This is the bit the several professional translators/interpreters I know had to do 4-5 years of university to get nailed down.