I find it frustrating that when importing config files I have to get all the way to a failed import before I find out that a module needs to be enabled, and if there's more than one, I have to deal with them ONE AT A TIME -- which is even more frustrating.
If we were able to show people on the synchronize page a list of unclaimed config files for modules that need to be enabled that would save me a lot of frustration.
Note: after https://github.com/backdrop/backdrop-issues/issues/1811 gets in, we can list the actual names of the modules and not just the names of their settings files (and a button to enable them!). But even the settings file names here would be a huge improvement.
Recent comments
You can use Rules or the Node Notify module for comments. When a new account is created, I believe there are Rules to send.
Email notifications
There's a few way to accomplish it, but it really depends on your full requirements. I'm working on a contact management module but it won't be released for a few months. There...
Pairing fields
I'm fairly sure that some people have done this successfully in Backdrop. Please can you list the modules you are using; that should help us get the right people to join this conversation.
How to render facet blocks?