Really nice set-up Varun, I have a few things to suggest:
Take out any access/side panels and open the chamber up as much as possible and turn off the fans!
Then you can try one fan for abit and see and slowly put back some of the glass and see, my plants are essentially in the open and they love it! Humidity can be around 50% or less for the HLers.
Definitely add more lights! I have 6 T12 fixtures for 12 tubes over my HL chamber and I have plenty of distance between them and the plants, but not as much distance you have there.
If that's a window above the tanks, I'd have them open as much as possible, spring/fall. Fresh air is good. Very good.
I AC in the Summer (2 mos) just to keep them from getting over 80F for too long. It's like maybe down to 70F at night. Temperature is not just numbers though...
Winter is pretty chilly rarely getting 70F and down to like 48F at night for a couple of months. Spring & Fall are their favorite... but it works overall. I've had healthy plants for years and the Sphag is extremely happy there and I only water like once every 3 days or so and that's the only time I mist as well with a hand sprayer.
Hope this helps!