"The Olympic Games will be held in America this year."
Translation:Οι Ολυμπιακοί αγώνες θα γίνουν φέτος στην Αμερική.
So how does "will become" turn into "will be held/take place"? Is this just another meaning of the verb, altho I can't find any trace of it in the dictionary, or an idiomatic thing?
I'm not sure what your dictionary says, but Wiktionary lists four basic meanings ( https://en.wiktionary.org/wiki/%CE%B3%CE%AF%CE%BD%CE%BF%CE%BC%CE%B1%CE%B9 ), the second of which is "happen", of which the first submeaning is "happen, occur, take place".
That entry says it's restricted to third person singular but I think that's the basis of how this verb is used here.