Like Janp said, I'm expecting this event to not make it internationally. Most of the time a Japan event gets an international release is mainly to coincide with a TCG release or something related to a movie.
Gone forever for personal reasons.
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So Shiny Silvally is Yellow. It is good news for Japan they are getting a Shiny Event Legendary. Yes it is obtainable in-game but people either did not know it could be soft-reset for (I assumed it was Shiny Locked like the Tapus) or did not wish to spend time SRing for it.
Shiny Tapu Koko (A Great Shiny) and soon Ash Hat Pikachu (A fun event) got a worldwide release but I will not be annoyed if this event is Japan only as it is an underwhelming Shiny.