Usually LED light control 'pods' are *NOT* rheostats. They typically work by PWM, with a $0.10 MCU controlling the PWM dimming and a MOSFET per colour to drive the LEDs. If it *is* a rheostat, it will get noticeably warm at half brightness, more so than at full or minimum brightness, but I would expect a rheostat to have a rotary knob, control wheel, slider or multi-position slide switch, not momentary push buttons.
It may be possible to replace it with an actual rheostat, but as Konkedout has pointed out, rheostats capable of handling several watts of dissipation don't come cheap, especially if you have to buy several because you don't know the required resistance range. I suggest searching for 5V PWM dimmer modules, with a rotary knob, not buttons or touch switches.