The new App for notifications seems great and a simple implementation of the RM to this specific need. Well done.
Would be possible to add Co2 to the list of Sensors?
Would be possible to add, as an optional argument, to Co2 and Sound a threshold level? For example if sound detected only above X dB?
Also could the lock code functionality be enhanced? I was going to move the lock code usage notification to this app, but then realized that each lock had to be set up separately so I quit.
What I am looking to do is have any lock report when a lock code is used and ideally be able to use a generic message with %device%, %value% and the lock code: "Front Door Lock was unlocked using lock code Denise"
Yes, "Any Lock Code" but only for one lock. No option to select all locks.
I don't have more than one lock that supports codes. I could setup a virtual lock to test I suppose, but doesn't Any Lock Code with the variable %device% as shown in the app cover any device with a lock code?
Did I miss something? What new notifications app?
Apps > Add Built-in App > Notifications 
Install Built-In app Notifications
Haven't tested, but knowing how apps typically work, my guess is that when I select a lock then the app subscribes to that lock, so it wouldn't know about the other locks. I wrote my own app to notify me about lock code usage so that works for now, but I'd like to move a lot of my notifications to the new notifications app if possible.
Correct. It can only be setup for a single lock. It's the same way in RM however. You can only select a single lock to trigger on lock codes.
What is %device% used for?
I don't think HE customizes it based upon specific apps, if that makes sense? It's the same across all the built-in apps. So, even though you have a multiple select option for "device" (like Contact Sensors, for instance), the %device% variable always performs the same way.
I think what @corerootedxb is trying to say is that the text notification area doesn't check to see if multiple devices were selected, it supports reporting the device name no matter what. So I could set up one lock and not have to hard code the lock name in the message, the %device% would report it.
How many locks can one have that this would be too challenging to setup? No offense intended @denise.grider
No offense taken, but why can't I select more than one lock??
Yeah, it's a template that is used in all notifications. Basically, the Notifications app and Rule Manager (and other apps that implement Text/Audio notifications) all use the same text.
This is from RM. It's exactly the same as it is in Notifications.
And this is from HSM. Again, exactly the same text.
Because it's a parent with child apps. One device per child app.
Probably your first assertion is correct that the event can only attach to one lock at a time. It might just be something that HE overlooked or perhaps a way that the event subscription model was coded originally.
I'm not on the HE team, so I don't know for sure, just applying my developer's logic to what it might be doing on the back end. 
I think you can select multiple contact sensors, so why not multiple locks? Shouldn't make a difference about parent/child.
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