Hi Ive,

The timeline component itself is 1 shape, so configuring a Tooltip shape data field will just show the same one each time. Unless you use a session variable to fill in the tooltip value, which is a text that is based on the selected variables of the timeline.

However, there is a shape called Reservation shape. You can dynamically update such shape with the selected reservation via variables. I would propose to create a details panel with such shapes and add tooltips on the shapes.
Hope this proposal would grant your desired outcome.