Lemmy is the whole of federated instances. Beehaw is one specific instance. Jerboa is an app that allows you to navigate and interact with others on Lemmy.
Think of communities like beehaw as neighborhoods. The actual community groups are houses in those neighborhoods, and the town made up of all the different neighborhoods is Lemmy. Jerboa is the vehicle you use to visit different neighborhoods and houses.
True, but the big surge in popularity should help with getting more positive pressure on the community devs to improve things rapidly.