We track enhancement requests and bug reports in GitLab. Our bug tracker is well-organized and issues are investigated systematically. See our bug reporting info page for useful links and details.
You can find us in the our Matrix room at #pitivi:matrix.org. Our Matrix room keeps the history of the messages, so if you lose the connection you can see the entire conversation when you reconnect.
For those still attached to their IRC clients, connect to OFTC and join the channel #pitivi. The channel is bridged to the Matrix room. The IRC channel should be used as a last resort, most of us are in the Matix room.
Do not hesitate to ask questions, and do not panic if somebody answers your question immediately.
If you need to speak to someone in particular, you may try mentioning the nickname (ex.: "nekohayo"). See also the main list of people involved in the project.