I just saw through SSettingsEditor.cpp which I think handles Project Settings’s slate.
That class and DetailsView class both have the FNotifyHook interface.
By looking at the way SSettingsEditor.cpp has implemented NotifyPostChange which is a function of the interface I found out that updating config files for config properties of the Project Settings happens there, but the implementation of NotifyPostChange in DetailsView class is so simple, so I have decided to derive from DetailsView Class and override NotifyPostChange by just copy pasting the code from SSettingsEditor.cpp.
I hope it all works, i’ll tell you guys
Update: Yes, with a bit of manipulations and o bunch of other common tricks what I described above worked. Don’t forget to add SharedSettingsWidgets to your “public dependency module names”.