I recall when the "name overlay" feature was added, there were long discussions about what colour the text should be. Taking all the possible "backgrounds" to the text (selected or not selected, blue waveform, grey background and
Spectrogram view, yellow was about the only colour that was readable in every situation.
As the colour scheme in Audacity becomes more customizable, I expect that this will also become customizable, but that will be in the future.