Yes that is correct. Your phone needs to be in Russian for objects to drop. I have not even changed my phone to English, my phone is in Russian for the next 8 days.
After one day of playing the event, and almost finishing it (FAST!) My suggestion is to first build your Attack Plane Hanger. Buy a Powerful Propeller Driven plane by selling some of your Jet. I know you have a lot of Jets because you go to North Observatory a lot.
Then fly the Powerful Propeller Driven plane to Cyprus to get Green Paint, Oil Container, Gun Camera, and Fuel Pump. Then get materials to build an Attack Plane by flying to Murmansk.
I am very fond of my many Jet (6)