I guess it can work, a lot of trimming to keep the coleus growth in check. I have just started to grow coleus this year, and the small seedlings are giants right now, that's why I am not sure about mixing it with semps. Maybe for a very temporary arrangement it can work. The other thing is the soil and watering needs. I find my coleus thirstier than the semps, so you might risk rotting the semp or if too less water, the coleus will suffer. But the again, my location demands that amount of watering for my coleus to survive the heat and just fine and dandy for my semps. So if your area is cooler, then it can somehow check the growth of the plants and will thrive just right together in that set-up.
It will be fun to see how that goes with your plants Joanne. Have never done that type of combination so I will watch how yours will go.
