2 possible visual improvements:

qtractorTrackList.cpp line 1248:
If we reduce the contrast of the embossing light, a more integrated visual result remains.
It is closer to the default "inset outset" border effect in Qt Fusion.
It can be seen in the image. The embossing of the table header is taken by Qt Fusion's default qtractor.

Name on Clips:
The "Name" on the clips has very low visibility.
If the "Name" color is changed to white, readability improves.

For the example I have taken the most extreme situation.
I have selected the lightest color from the list for the background of the clip.
Knowing that the clips have transparency, I simulated it putting a white with 50% transparency.
I think that the transparency in the clips is inferior, and despite that, the readability gained is notable.

Greetings