If you compare the bars to your x-axis, you’ll notice that two bars for a year are to the left of a tick and two are to the right. Also, you are using a linear x-axis scale rather than a time scale for time data. Without looking at the tests and doing some hacking on your code, my guess is that you’ll need to move the bars so that the first bar for a given year starts on the tick and the others follow to the right. You may also need to use a time scale for the x-axis to make the project’s tests work correctly.
The tooltip issue is similar to many others posted in the forums.