In the past i've been tooling with porting Lineage 2 animated creatures to NIF format (gamebryo). The thing was, when i exported to NIF model+animations from a fresh import, all what i got was messed up animations,
Yea it looked like that it might be a problem with NIF exporter but it was not, i've digged some older version of your actorX plugin and to my surprise animations exported correctly. Now i want to experiment some more but i lost that old plugin in a HDD failure. For now i use a workaround with exporting/importing as an FBX and then to NIF.