Currently, the NS groups my Pandora stations first and then my Playlists. Would it be possible to place the Playlists first (which change less often) and then the Pandora stations? Since this may not be everyone's preference maybe via a configuration option?

In my case, when Pandora stations are created (sometimes accidentally) outside of Volumio, any programs that reference a playlist are affected (since the NS inserts the station above the playlists).

If I'm not making this clear, I can provide an example.

It's clear but it's not the node server doing the grouping that way, it's Volumio.  The node server does a browse at the top level and creates the entries based on the order it see sources in that browse.

Given that what is available in the list of sources will vary for each Volumio device and the order may even depend on the order sources where added to Volumio, that's a fairly complicated ask.