Go and talk with the people who wrote it. Often times there are a just a handful of people that wrote a lot of the core functionality, they often aren't the most social. Talk to them when you are in the planning phase of implementing something.

Lots of great advice here that I agree with. IMHO though I see a lot of engineers miss on the team and social aspects of coding. Just as important as your tech stack is your team. Have an idea for improving something? That's great, but remember to listen first and learn to love what is great about the way it is. For you it could be X% better for the original authors it is a miracle that they made it work at all and it is important enough to need a bigger team.