I'd say that it's more important to have the center placed so the front baffle is even with or in front of the TV screen. Anything placed forward of the center will generate reflections and filtering that would negate any benefit from wall-mount. So, unless the TV is flat against the wall the center shouldn't be either.
Note that there are ways to hang a center from the same articulating mount that the TV is on, assuming it can hold the weight. Some of the TV mount makers even sell shelves that hang down under the TV. Obviously the LC2 is big and heavy enough to challenge any shelf or mount. But you could even use a separate articulating mount just for the LC2 or just a very deep wall-mount shelf. I'd like to see your LC2 up under the TV screen, both for alignment with the TV and with the L890s.
Also note there are entertainment tables that have TV mounts on the back with enough room under the TV for the center.