You can use any name and any location for a texture - etc

The Poser file just must know where it is.  You do that by editing the path in the cr2, pz2, hr2,...  It can be done using a simple text editor, but a dedicated Poser file editor makes this much easier to do.

If you put the texture in the folder with the cr2/pp2/... or a sub folder in there, the path need only be the texture name itself ( if directly in the same folder ) or the sub folder name and text name if there,

A cr2/hr2/pz2/pp2/... can be in Hair or Prop or Pose or Figure or Camera or Face - and it will still execute.  You just must double click it.  The specificity of a Poser Library section is that the launch checks at the bottom of the Library only work if the file extension matches its section ( hr2 in Hair - cr2 in Figure ).

If your textures/ obj/ material poses/ pmd   are only used by one cr2/pp2/hr2, why not keep them all in the same folder ?  Just make sure the path is correct.