I don't use the File Order Placement on my DrivePool, but as I understand it, you can order your drives in the priority they should be used. If you designated your 12TB Seagate Exos as the last drive to be used in the pool, that should significantly reduce the writes to that drive as long as your other drives with higher priority have free space. At the same time, you could also manually transfer files to/from your 12TB Seagate drive when you want. If you have files on the 12TB Seagate that you constantly need to read, then I would manually move them to another drive.
If you have lots of frequently used files to move off the 12TB Seagate, then you might consider to "Remove" the drive from DrivePool, have DrivePool empty its data from your 12TB drive, and then add the 12TB Seagate back in again to the pool as the lowest priority drive in the pool. Then you could manually move rarely used files to the empty 12TB Seagate and basically have the 12TB drive there as storage. I think that would work. I'll be reading this thread to see if there are other ideas.
