I am using ubuntu mate since long and have been using Traditional Mate theme since start. I have since quality improvements, especially in placing missing icons in the themes during my usage. However there are some issues that are quite jarring to the eye that still persist. I will list atleast two now and request someone to correct the anomaly:
There is a problem with lower glyphs for letters such as 'pqjy' (red underline) in the title bar. Illustration
while the letters with upper such as 'dbitl' look fine the letter 'j' looks almost like an 'i'.
There is a discontinuity that is observed, between title bar and menu bar (red circle), when we un-maximize any window, which is quite observable. Illustration
this is noticeable in all application weather the window is un-maximizable or not. (for eg. you can un-maximize pluma whereas you cannot un-maximize user and group window but this discontinuity is observable in both.
I hope that i have used appropriate forum to bring it to your attention.
Thank-you for reading.