those are all good ideas. 62-74 should be growing fine though. are your pots directly on the floor? you may want to raise them, it'll warm them up a bit. i'd recommend slowing your fans like you did, and maybe a slim radiator in the one that needs more heat like this one
https://www.amazon.com/NewAir-Portable-Heater-Electric-AH-400/dp/B009L40S0S/
or use your bud heater on a thermostat controller.
I bought this. I will connect it to a Inkbird temp controller. https://www.amazon.com/gp/product/B009L40S0S/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
I had this dilemma before. Trying this heater this year.
https://www.amazon.com/NewAir-Portable-Heater-Electric-AH-400/dp/B009L40S0S
Just got mine set tonight actually.