Changing the workflow State through the API

Yes you can, the workflow and state are both properties that can be updates like any other property on the metadata card. The WF is def id 38, and state is def id 39. You just have to know the ID of the wf state so you can set the value of the value list. 

Someone posted some code about how to do this on a post earlier today. Below is a reference:

https://community.m-files.com/forums-1552881334/f/general-discussion-feedback/6467/how-to-create-an-obj-inside-a-particular-workflow 

Thanks!