Hope you'll forgive me if I've misunderstood the library management questions. I would manage a Kodi music box in the same way as I manage my films and shows. Which is my LE box in the TV room (cellar) pulling its content from a NAS in the office upstairs. Isn't that what most people do with their Kodi / LibreElec boxes? Though hopefully not from my upstairs office.
Yes, that is what most people do. But I've found having multiple clients each populating their own library to be a bit cumbersome/inefficient if you have a large music collection. They all have to update, they all can have the same scraping errors, etc.
Some create a central MySQL library to help, but I've found that requires me to update all the clients at the same time, which if you are using regular KODI and also LE those updates aren't even available at the same time.
Then there is often a desire to play music on other devices. For me that would be Chromecast Audio. Having one centrally managed music library that feeds all clients can be a very nice thing. If one is going to the effort to create music dedicated clients, it is something to consider.
I have switched to PLEX for my music library, and access via the PLEX addon in KODI. It has simplified my life.