How to resize tongue in wickedwhims?

I have a feeling it's because the Rig files aren't in the package with the tongue model you're exporting.
They need to be there so the weights get exported (and imported) with the model.
If it's already a custom tongue just batch export all the Rig files from the WW .package (or wherever the tongue gets its Rig from) and put them into your package.
You can remove the Rig files once you are finished making modifications.