Every time that someone joins our team at work, we always get an email saying "please welcome the latest addition to our team". The word addition is always used. I personally have no problems at all when referred to in this way
It sounds perfectly fine to me in AE as well. I understand your concern that the team will be treating the new person like an item (similar to a new computer or the like), but it is a very common phrase in English and means something along the lines of "Although Samuel is new to the team, you will find that he will help the team greatly in his area of expertise."