I transplanted an old azalea last year. I did not cut the trunk back. I only do that when a plant has become scraggly looking and needs rejuvenation. If, however, in the process of moving your plants, the roots get disturbed a lot ... perhaps during the separation ... you may
find it necessary to prune back the top growth a bit.
Make sure you water the azaleas every day for the first several weeks. You don't want to drown them, of course, but you want to keep the soil moist.