In the Moodle version on the MoodleCloud the back, forward links and the jump to box are superimposed rather annoyingly over the content from the Lesson page as in this image:
What can be done to stop this irritating glitch in the Moodle Lesson module?
Have you made a note of this in Moodle Tracker? This has to be taken care of by the people maintaining the MoodleCloud, so leave it for them. The other side is that the maintainers of the Lesson module will need to be alerted, because while this is likely a theme issue, it should still be addressed by several parties.
The other question is are you doing something in the MCloud Lesson that others are not? There seems to be a lot of images in that graphic, so have you considered that it might be the way that you set up the Lesson? For example, could you place those images in a <div>images</div>, making sure the dic has a clear start and end point? That may push the links to the end of the <div> container. I am assuming that you have access to the HTML code in the Lesson editing screen in MCloud. Manually enter a <div>, give it some properties, maybe a border, a set of border padding values and so on. See what happens. Cheers