Hard to understand the architecture when there is so many moving parts which makes me not want to use it for my own stuff. Because if I don't know how it works how can I fix/change it when I have to? Also the loader icons last for worryingly long time when I'm running it on my localhost. Which means the caching isn't working as it's supposed to or should it really take that long to load a single webpage? Not trying to attack on anyone here, just observing.
How is your serviceWorker configured? The problem I have had with them is the N+1 (or sometimes more) times it takes to reload changes which is infuriating to me and I've stopped using them altogether since the benefits aren't that great (for me at least).
Maybe if you could bootstrap with this step by step it would be easier to get to know the structure a little better. So say you could first bootstrap à la create-react-app with bare minimum to get things rolling and then add on caching features which there seems to be plenty of.