Oh yes, my reply wasn't definitive. But a few comments:
Whether you say 'has become' or 'became' depends on what you are trying to say. They are both correct English but have different meanings.
If I had to choose between 'build' and 'make' I would choose 'build'. But really, there is very little difference here. (I am talking about kites. You might say 'make a cake' but you wouldn't say 'build a cake'.)
'Buteo's lifelong passion is making and flying kites.'
That sentence means that Buteo has only one passion, whereas the other sentences leave open the possibility that he has other passions.