Phonograph2 is based off ElasticSearch but has a few differences that can sometime throw the following error message:
errorCode: INVALID_ARGUMENT
errorName: Conjure:UnprocessableEntity
How to find out the set of valid properties that can be used for the phonograph2 service API?
On your Foundry instance you should be able to find the API definition for Phonograph2 in the documentation at a relative URL like
[myFoundryInstance.com]/workspace/documentation/developer/api/phonograph2