Thx for the feedback. In fact the tool is completely rebuilt in the next edition. It’s not longer triggered on hover at all. We made this change mainly because of usability on mobile, but also general concerns about accessibility of tooltips: they’re bad for anyone with motor control disabilities, for example.
Now you click and the word appears in a sheet at the bottom of the page. You can go forwards or backwards be either clicking a big button or using your keyboard.