For starters, as
@cromag08 always says: leave your pop in the refrigerator
Are you talking about after some amount of time in your tank, or immediately after bringing them home?
Did you use any kind of light meter to check your old lights before switching so you could see if intensity was the same or at least similar?
If you still have the old fixture, do the comparison now.
If you don't have a light meter, start with a
free lux meter app for your smartphone. It uses your camera's light meter to compute a normal lux reading. "galactica luxmeter" on IOS is one of dozens of similar apps. I'd suggest ordering a $15 handheld lux meter from any of the online resellers. Search for the "LX-1010B" or similar. It'll give better readings and is going to be safer to use around your tank!
Try to match the Kessils' intensity at the water level with readings from the T5 fixture at the same distance from the fixture.
It'd be cool if you reported back what you found for your readings too!
Since you've switched from T5 to a spot-type LED fixture, I also suspect
@andys could be right about needing more fixtures. Though I think so for different reasons - shadows and coverage. Matching intensity with a light meter may fix the coral color issue, but it isn't going to do anything about this. Additional spot lights do help to cut the intensity and size of the shadows, though, in addition to giving you the option of more intensity. Light still won't be as shadow-free as T5 light or strip-format LED's though. Of course whether this is a concern is mostly up to
@willthethrill's tastes and intentions for the tank.