Hello nyudeb,
So whenever you import any .fbx file into your project, those files should then be converted into .uassets automatically. For example, I have a set of .fbx meshes that I have imported into the Content Browser and placed in a folder I called ‘Meshes’. I opened the folder within my unreal project directory, and they were discovered/converted into .uassets.
This commandlet is so new that it does not have any documentation for how to implement it correctly, so I might log a ticket to have that addressed. This should work without the need for a commandlet, but if I am missing something let me know.
Thank you,