When a task has subtasks (or if a project has tasks), sometimes comments and discussion can get buried under a nesting of tasks. Slack has a feature, when replying to a thread, you can choose to add your comment to the “parent channel” in addition to the thread. I think something like this would be really helpful for finding and following conversations within a project or a large task. This way, comments and discussion still occurs around the subtask topic, but can also easily be seen and followed by the parent task followers.
Furthermore, these comments and discussions could/should also be added to the project’s conversation tab. If you have ever used or seen Twist, they have channels, and within those channels they have individual topics/threads. Conversation occurs within inside those topics within the channels. I envision Asana’s project conversation tab being similar to this concept. Somehow, all of the comments that occur within the tasks and subtasks of a project need to be collected, organized, and searchable within the Conversation tab. Perhaps you can add a “breadcrumb” label to each comment that helps you locate the comment and perhaps understand context. By “breadcrumb”, I am referring to the way Google Drive displays the path by which to find the file or folder you are looking at (similar to the file path in Windows Explorer).