Folder for Tilesets in Tiled

Is it feasible to establish a folder containing all tilesets? Importing tilesets repeatedly can be tedious. Ideally, I would like a unified folder in Tiled for tilesets, with the ability to create subfolders like “buildings,” etc. Is this functionality available, or could it be incorporated?

What do you mean by “importing” tilesets? That’s usually not a done thing, you just open the tilesets you need and use them.
If you use a Project, the Project Panel will display all the Tilesets and Maps within it, so if you have all your tilesets in a directory (and subdirectories) within that Project, you can browse them all easily, and add them to your maps as needed.

If you’re asking to create Tilesets automatically from images using the same tileset settings, then no, that’s not a feature, but that is a task you can automate using Tiled scripting.