Thanks for your work, serebit!
I hadn't have trouble with the system tray, I mean no real trouble like things not working or stacks of icons covering each other or such.
I had noticed though - like GuzziPhil - that sometimes I would see the icon info and sometimes I wouldn't (I cannot see a grey line showing under the icons like he can).
That is still the same, probably due to what you explained to him.
I work on a Thinkpad T480, have Plata-Compact/Papirus/Adwaita installed and cannot see the info for these icons:
Caffeine, Night Light, Time/Date/Calendar, User Indicator.
On the other hand I can (reproduceably) see the info for:
Network, Battery 1 & 2, Volume, Bluetooth.
But I must say not being able to see those infos hasn't bothered me and is not that important.
I didn't notice the better spacing between the icons at first but now that I was pointed to it - hooray, it does look better indeed! Thank you for making SOLUS better!