mojave – How do I change the appearance of the volume and brightness overlay in dark mode?

As you all know, Apple released a thing called Dark Mode in MacOS Mojave. My problem is that I got used to the previous appearance of dark mode when there was only a dark dock and menu bar. I've found that I can enter a command in Terminal to restore the previous view:

defaults write -g NSRequiresAquaSystemAppearance -bool Yes

That worked well, BUT there is a problem. Not everything became really white. For example, the language switch remained as a white text over a white background, which is not really readable. Brightness and volume controls remained as dark cells over a dark background, which is also unreadable. Pictures below:

Illegible volume control

Illegible brightness control

Illegible language switch

The appearance of the language switcher was entered by typing:

defaults write NSRequiresAquaSystemAppearance -bool No

After that, it got completely black (like a normal dark theme), that's alright for me.

Readable language switch

I believe I can do the same with the audio and brightness overlay. The problem is that I do not know the specific name of this UI element to address it with this command. I want to change his appearance into an easy one. Is there a way to do that?

One more thing – is it possible to change the color of Notification Center and notifications yourself? They also stayed completely dark. I prefer to see only the menu bar and the dock in the dark. I would be very grateful if there is a solution to my problem. Thank you in advance!