No, you only need to achieve one goal in IT5. You decide which goal (which contest) for your domain on the local poll.
For example, the Italian community decides they want to name 555 villages ending in -ix- They do this and they win. Italians have done their work.
But the other communities have their own contest too. Germans, Czech, Polish... The rewards will only be unlocked if 6 out of 11 communities reach their goals.
So at least half of the domains have to reach the goals, then everyone gets it. You can help in the Italian community, but not the others. (Or you can, if you speak or want to play in other languages)
I hope that's a bit clearer. If not, ask me any questions you might have