So… in theory one might be able to take a NWN animated mesh, attach an empty to each mesh, create an equivalent NWN2 skeleton, attach empties to those bones, then constrain the skeleton empties to match the translation of the NWN meshes. That should, I think, cause the NWN animation to animate the NWN2 skeleton.
Can one export the result to a Granny file though?
If you create an equivalent NWN2 skeleton, I think you could constrain it directly to the NWN meshes, without using intermediate empties. I don’t know the details about NWN meshes, so I’m not sure. If you have a Blender file with the NWN animated meshes and the equivalent NWN2 skeleton, I could take a look.
And yes, you can export the result to GR2. Even if the skeleton is animated only because of constraints, when you export to FBX, the animation is baked for the skeleton.