At that age, my male panther was eating ~10-15 med. crix/day, split between 2 meals.
Yours really should be getting some variety. IDK what worms you've tried; have you tried small super worms or giant meal worms? I feed out of a home-made feeder run cup similar to
Full Throttle Feeders style.

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Does he know that's where the food is? If you haven't already, try holding the cup with feeders in it below and in front of him so he can see the food. Once he starts eating out of the cup, he'll associate the cup with food, and you should be able to relocate it.
It's beautiful.
Yes, I would remove anything artificial. The plants you have will grow into beautiful strong vines along with your cham's growth.
Lights:
UVB : T5 HO w/ mirrored reflector. Reptisun 5.0 or Arcadia 6%. Both are good. Fixtures that look like this...
are all made by the same company, so shop for price. Doesn't have to go diagonal, but diagonal is OK. Should at least go full width of the enclosure, so 24" (nominal).
Plant light: For your enclosure & plants, I would go right for a Sansi 70W LED grow light pad.
https://www.sansiled.com/70w-led-grow-light-full-spectrum.html
Look for coupons:
https://www.google.com/search?client=firefox-b-1-d&q=sansi+coupons
Basking light: Old-style incandescent household lightbub (current dome fixture is fine). If you can't find one of those, incandescent flood (NOT LED) or halogen flood (NOT LED).
In lieu of one of these, you can use your CHE, but it should go off at night unless nighttime temps drop below 50F/10C.
I don't see anything alarming about temps, but he may be sleeping low in the enclosure seeking cooler nighttime temps.