I think the persistent notification thing is something that will have to be addressed via firmware. As I understand it, it is, for all intensive purposes, just a “light” that can be turned on or off. When you add another notification, you are merely switching with “light” is turned on and therefore you lose the last state. I am not sure if there is onboard memory for the switches, but that is a bit of logic that needs to be handled locally on the switch to get the result most people are looking for. Not saying that it can’t be done, just that it will take some work on their end.
I think what Inovelli has done in just giving us notification lights generally at the switch level is pretty intense and the way they do it is fairly eloquent. I’m not saying this isn’t a good feature to add giving that most people when they hear notifications, they immediately assume stackable. I just don’t think the device is currently coded for this.
All that being said, I am fairly certain a pretty simple piston in WebCore could be written to at the very least understand TWO stacked notifications. It would just be a matter of detecting whenever a notification is “turned on” and storing a value for that notification. If another goes on, doing the same. If the current “notification” is then turned off, the piston would check if there is a stored previous notification and if so, turn it back on. I’m sure I’d have to work through the logic a bit to make it fallback correctly, but conceptually I worked it out and should be able to be done. If anyone REALLY wants to go at this, I can try to carve some time to build out a piston to try my theory.