OP mentions there's no way to get the tasks assigned to a column for a particular project.
I tried diving into all the related fixes, but it doesn't seem like this particular point was addressed.
I investigated a github library (https://gist.github.com/robwiss/9c7e2bcf2af063635288) that goes through some hoops to associate the tasktransaction transactiontypes of type projectcolumn, to figure out what column the task is currently on. However, in my Conduit queries for tasktransaction, I'm not seeing any transactiontypes for any of my tasks that are of type projectcolumn.
I'm not sure if this might be some sort of regression or bug, where projectcolumn is no longer returned with queries for transactiontypes.