The web creator lets you add, move, insert and delete track points. Work on a small section at a time and use Undo and Redo while comparing the result.
Check how the edited section joins the points before and after it. After refining several sections, zoom out and inspect the complete lap rather than judging each change in isolation.
Give the track a clear name and save a separate copy before a major redesign. A bug report should explain the tool used and the smallest sequence that produces the problem.