I've not seen the European version of today's Nintendo Direct, but given the timing of Inti Creates' Twitter post, it seems likely that is where they made the announcement of when Azure Striker Gunvolt is coming to Europe and Australia.
Regardless, Inti Creates has made the news known loud and clear both on social media and their website: Azure Striker Gunvolt and Mighty Gunvolt both arrive in the PAL regions on... April 2nd! that's tomorrow!
The game will cost 12.99 EUR/16.90 AUD, and the download will already be updated to the version currently in other regions, version 1.2, without any additional downloading required.
Nonetheless, you'll still want to make one other download, as the same deal that North America and Japan saw applies here: Purchase Azure Striker Gunvolt before July 3rd at 12:59:59 am CEST, and you'll receive a free download of Mighty Gunvolt in its updated form, complete with access to the game's downloadable content!
Finally, one hour after Azure Striker Gunvolt goes on sale at 3 pm CEST, the same Azure Striker Gunvolt themes for Nintendo 3DS which are already available in the North American Nintendo eShop will be for sale at a price of 1.49 EUR/1.95AUD each.