You couldn’t start it doesn’t mean it doesn’t work. Any work, teamwork or not is useless when trying to fix something that is not broken. There is no „fix“ for it anyways, since the server is not multithreaded anymore.

When you contribute code, ideas, data, tools, docs, etc… you are a contributor. I don’t know what you are answering with this, but yes any help is a contribution.

It is mostly true that for a full project nobody will understand all of the code someone else wrote. For a small passage that is possible. The thing is that you don’t need to understand that part of the server, you just need to use it. I have to admit though that I still have to document my code.