Any chance you were able to figure out a solution? Having the same issue for Job Scheduling Board. Thanks!
EDIT: Tested in 2025.1.16 and adding columns are functional:
Added Part Desc, Labor Hours, and, from a post-process method call, Cust Name. It was really simple; All I had to do was add the desired field names from the SchedulingBoard data view to the Gantt Model > Columns settings
