Try this again, I hit the wrong button after typing a response.

Erik, since no one else has responded as of yet I will see if I can be of some help.  Hope this is not too late for you.

First, I assume you are referring to GMAW spray transfer and not short circuit as short circuit is much more limited and would require more testing and much more careful usage in this application along with being considerably slower.  Need PQR set up specifically for this job.

Second, you did not state the code to which you need to know of any limitations.  This info would be critical as they very so much.

Third, I assume you know the AWS defined difference between semi-automatic and automatic.

With these points in mind, NO, I personally do not know of any limitations on thickness if the proper PQR, WPS, equipment, operator, and inspections are used to complete the job. 

If this did not answer your question, please reply and we'll see if someone else with better knowledge will join this thread.

Have a Great Day,  Brent