Emily, if the geometry is in the Library (hr2) it is usually transparant to you - it just loads - The external call is when you get the "where is it" - I think. The advantage - now - for external call for hair -is if a prop only needs scaling, positioning, or a morph for it to fit Vic and Steph and Mike and MilKid and P4. If the geometry is 1 Meg - internal geometry means that you need five 1 meg files. If it is external call, you then have five 50 k files and one 1 meg geometry file.
Just open the wave.hr2 in EditPad and look. If it has a huge block of "v" lines, "vt" lines "vn" lines, "f" lines - at the beginning - this IS the OBJ file.
You can cut the geometry out, paste it into a new document, give a name with extension .obj and you have a for real geometry file. You have just let your TE export the geometry, instead of Poser.

If it has a path instead, look at the path and see if you indeed have a geometry file in that location. If not, either put it there, or change the path to where it is.

droyd, you are at a fork in the road.
One way is safe and easy, but your options are limited to what others provide for you.
The other is more difficult, requires trial and error, gets you scratched up at times, but lets you call your own shots.

There are generally two sorts of files in Poser:
Library files
Files that the Library files use.

Library files end in = cr2, pz2, pp2, hr2
You call them. The restriction on their location = they must be in the Library that their extension defines
cr2 - character
hr2 - hair

These files can be in any folder within their Library - after all, you are the one that finds them.

The files that the Library files use, must be where the files expects to find them.
If it is a geometry and the first call is incorrect, Poser crashes - out of memory sort of message.
If the first is correct, but the second is not, I think you get a bikini or something, it yells at you, but does not crash. If a second geometry is called, but wrong, no crash, but much strangeness.
If it is a texture that is wrong, Poser will try to find it. If it cannot, it will ask you - for every material - one at a time.

Geometry paths must be precise - really precise - or you will likely have a crash.
Texture paths must be precise - if you don't want to be bugged to death.

Both of the type files can be anywhere, not even on the same drive with Poser, just as long as the path is correct and the files are available.

The files are text files. Using a text editor, you can make the paths whatever you want. Using a cr2 editor, you can have it made whatever you want. You have control - as long as you follow the correct syntax.