Hi @anon94874620. Unfortunately you can’t have a task within a project that is private to only select project members. You can have a private task that is not associated with a project (private to only the task collaborators). In your case, you obviously don’t want the latter.
One option would be to have “client x - internal” project which is worked only by your team and then duplicate the key tasks or milestones for “client x - viewed” project. Since tasks can be assigned to multiple projects (up to 20), this would allow you to update both projects key tasks at the same time and allow private tasks or conversations to happen internally.
Here is a few past discussions around this similar topic. Hope it helps. Private task with shared project - workaround . and Professional services firms: how have you set up Asana to balance internal vs external communications with clients?