Hi hum … no event … will we get extra days at the end ?
No extra days. As the disclaimer states, the update to 1.166 is the requirement to play the game on mobile (should read "1.166.1 (...) zz 1.167" instead of "1.165.2 (...) zz 1.167). At best, the required mobile version gets released before the event start, but that's one reason why we include a disclaimer in the announcement, since we can't guarantee on Beta that the live release of the necessary version will happen in time.
The other reason is that the app platforms roll out updates in a staged way, so some players will always have a new update available before others have it.
Like Verde suggested, after playing on Beta in the Browser the event seems to work for the account in the mobile app, too.
I can't say if this is a reliable and bug-free workaround, so for now, I would suggest to play the event on Browser only if possible to prevent any issues caused by the different versions between the platforms.