I'm running 2 of those exact lights on a 55G. I have the whites on the lowest setting, and the blues on the 3rd lowest setting. My anemone is right in the middle of the tank planted in the crevice of a rock, about 14 inches under water and 20 inches away from the lights.
I've had it a week tomorrow. I think my nitrates we're about 40ppm when I put it in, and I've had an algae bloom for about a week now.
My anemone hasn't budged, at all. It pulled itself deeper into the crevice after I cupped it with my hand long enough for it to grab the edges. It puffs up when the lights come on, catches mysis shrimp that float close by, closes up to shed white mucus daily, closes up and sheds brown mucus when I scrub algae.
It generally seems pretty happy.
My tanks still pretty new, younger than yours I believe. I only decided to try an anemone because I saw what looked like tiny aiptasia, and while getting peppermint shrimp it donned on me that aiptasia is technically an anemone.