Sorry, didnt check the xda thread for a while, as this is my main thread. I cant say anything on how it behaves on oreo, but i guess you could just permanently mute the notification. I am not rooted nor do i have any custom rom installed obviously, so i cant even test on these configurations, but it actually should work as intended as well.
Did you install the latest version of it before posting here? If not, and even if so, go to the download folder and get v0.9 and test again.
Regarding substratum theme, i guess this is nothing substratum could do, as it only can take in account portrait/landscape but not landscape left/right which os important for button possition obviously. This is perfectly fine for curved corners, but in our case is not enough. Also i am not rooted, so no substratum
alright. I'm on 0.8 which is the one on xda. guess i'll try 0.9 and uninstall if it's still unstable. You can't dismiss that notification in Oreo at all, since it's from the system.