Yes, you are able to split the localization as you please.
In I2 Localization, the terms and translations are stored in Language Sources (which can import csv files or spreadsheets directly from google)
By default, there is a language source in the resources folder that is named I2Languages and that is accessible everywhere. Thats the GLOBAL localization source. Most of the time, all the terms goes there.
But you can also create Language Sources as objects in your scene or download them as a bundle. That allows you to have terms available only for some scenes or add more languages once the game is released.
All example scenes use the LanguageSource inside the scene. That way, the localization of each example is local to that example.
The other possibility, is to store all the terms in a Google Spreadsheet and link the spreadsheet to one of the languageSources. When the game is ran, it will automatically download any change. That will allow you to add or fix translations even after the game is released.
csv and language sources don't need to include all languages. That way, you can have a csv with english, another with french, etc.
Hope that helps,
Frank