Not sure on the LMB temp requirements, but they do fine in Oklahoma in the summer heat and the ponds end up feeling like bathwater. It may not be ideal, but they do live in it. I would be more concerned the flowerhorn is too cold so I'd keep the temp bumped up to 80 at least for the flowerhorn.
Not sure what line he is, looks faded out but that could be that he is just adjusting still or even too cold. His hump may grow a bit but I wouldn't expect much, his tail is a bit weak. A good diet and water conditions will bring out the best in him. Looks like e may pop some pink, green or yellow and blue given the chance.