Sorry for the miscommunication Ryan. Currently, the web service can only create trends on a display as you mentioned. There is no way to programmatically create other types of symbols. I think the statement was referring to the feature in PI Coresight that allows a symbol of one type to be transitioned to another type by the end user.
We have a backlog item to expand the web service to allow other types of symbols, but this work has not been scheduled yet.
Thanks for getting back to me about this. It would be a really nice thing to be able to do creating different symbols through the web services.
Look forward to it being implemented in the future.