With communitheme the snap applications Terminal, Calculator and System Monitor used transparency.
They are now working on my Cosmic Cuttlefish installation. The transparency is gone. There are however some error messages.
Code:
Jun 2 07:59:58 pi-MS-7A34 gnome-calculato[14759]: Theme parsing error: gtk.css:2662:72: The :insensitive pseudo-class is deprecated. Use :disabled instead.
Jun 2 08:01:08 pi-MS-7A34 gnome-terminal-[14909]: Theme parsing error: gtk.css:2662:72: The :insensitive pseudo-class is deprecated. Use :disabled instead.
Jun 2 08:01:33 pi-MS-7A34 gnome-system-mo[14932]: Theme parsing error: gtk.css:2662:72: The :insensitive pseudo-class is deprecated. Use :disabled instead.
It's not working on Ubuntu 18.04