When using your dicterm cli, I get the following error when running dicterm prognosis.

dicterm prognosis
# could not unmarshal response, err: could not unmarshal response: json: cannot unmarshal array into Go struct field Collegiate.ins of type string

For the moment i think it's easiest to set the type of the attribute corresponding to ins to any and use type assertions in the dicterm api.
It's kinda ugly, but so is the merriam webster api, lol.