Localisation in RPG Maker is something I've been thinking about for a while. In the older days of RPG Maker XP many Japanese projects actually put all their dialogue into common events (yes, all of it) and then at the end of development they'd open up the common events manager and translate all the dialogue to English then re-publish as an English release.
With MV using JSON as its data-format, my plan is to write a tool that essentially creates a database of dialogue from all the events in the game data, then converts that database back into the event data for additional languages.
Of course, this method is offline translation and requires separate installs for each language. Not the best solution, however one angle I'm going to investigate is having the translated database itself be a hot-swap for event dialogue as it is loaded in the game (via a Plugin). So the production pipeline would be; create game as normal in one language, generate translation database, translate to multiple languages, create Plugin that dynamically swaps text out for that in the translation database as it is encountered in the game.
From this, I can have the language be selected based on the player's Steam language settings and then let them change it within the game options menu too.