My boss decides on new languages/frameworks almost each new project...

These are the number of different languages/frameworks we are at...
Back end:
5

Frontend:
4

Sometimes it looks like he is trying to even out by 10 :)

At least gives you the chance of learning something new. On the other side, you cannot really enjoy your extra knowledge of that particular language. :(

@brunofontes the real problem is the lack of focus on anything.
We are always trying to learn something new while dealing with tight deadlines and everything just turns into a snowball of endless spaghetti.

Instead of delivering what we mastered in time and dealing with new things on side projects to see what fits best into our culture.