We can run this by the dev team for you. As you guys are using the REST API to control your config you could likely implement some sort of validation check before you submit the change to your games config. If the updated property is invalid simply don't submit the change to the games config. Does this sound like it might work for you ?
Oh yes, totally! This is by no means a mission critical request. It's something I noticed was missing that I thought other people might find useful after making some mistakes hand-editing some Properties.
Because Properties can currently be edited by hand, it would be nice to be able to validate the contents of Properties against a schema to ensure correctness of property names and values.
The Configurator and Property API should warn the user if the JSON does not match the schema. It would also be nice to optionally prevent updates to the Property if the new document fails validation.
A specification for a JSON Schema language can be found here: http://json-schema.org/
Newtonsoft offers an online validator against this spec with source code: http://www.jsonschemavalidator.net/.