I've run in to the situation where my highlight's text overlaps with the label for the signal. It seems like there should be some skinparam options to move this text to the bottom of the diagram. Another nice option would be the ability to center or right align the text for individual labels.
I am using PlantUML version 1.2020.15.
This is an example of the problem. This is a robust signal which has a label "Encoded Data". I want to highlight the first section of the signal and the highlight's text is "Sync Pattern". You can see that the texts overlap.
I have several workarounds: I can move the text to the right by inserting something like <U+0020>, I can drop it down a few lines using \n, or I can start the plot at some negative value to drag the signal's label to the left.
It would be nice to be able to control the placement of the highlight's text, such as place it at the bottom of the plot, center it horizontally, or right justify it horizontally.