Hi, My great grandfather also was born in Heinstert. He immigrated to the US, living in Allegany, N.Y.
I was in Heinstert a few weeks ago! The church is still being used, but alternating services with other villages. There are too few parishoners and too few priests to have all churches running all the time. We were told this by a local woman. She tried to get the key for the church but the lady who had it was not at home.
Do check the message from Lloyd Mans (Wallonia board)who also has acestors from here. He may be able to give you contact information.