Anyhow, the question "Who is my neighbour?" is an old one. It works for countries, it works for people who live near you, but it doesn't work, as an adjective, for work colleagues.
Ok got it! :-)
So I will use "neighborly" strictly when talking about residential neighbors instead of others.
Regarding "sympathetic", it always gives me an impression that it is used to describe miserable situations that you feel sorry/ pity for something sad (so that it does not seem natural for describing a colleague who simply likes to help others, which is not sad at all.)