So the real key to this is doing something with the energy before it becomes the unknown wobbling mess of thermal energy that turns your witch into a pop tart. If you generate the heat, you have to get rid of it, period. The only real solution is to minimize the rate of heat generation.
Consider how one can use capacitors or inductors to shape current flow. If there's too much voltage, you can bleed some of the energy into a capacitor and release it later. Because you released it back into the system, it doesn't get turned into heat. If you had used a resistor, you would have had to convert it all to heat. They make big resistors for that, but you don't need them.
So your channeler never tries to fix anything by opposing it. They simply bleed some energy into themselves when there's too much in one form, and emit it back out in the other. You can be arbitrarily good at this.
The other big thing you may need is a failsafe. If your channeler isn't very good, and gets in trouble during practice, it'd be nice if they didn't die. For that, I'd recommend taking a lesson from High Voltage Direct Current (HVDC) lines. HVDC lines have to have a circuit breaker, like all power lines. However, this is difficult. Normal AC power cycles at 60Hz. This means once every 0.86ms, the voltage across the circuit breaker is zero. This extinguishes any arc that may form between the electrodes and makes interrupting the current comparatively easy. Doing it in the HVDC world is harder because the current is never interrupted.
One solution is the "hybrid" breaker. This approach is based on the observation that there's two kinds of breakers in the HVDC world. There's slow mechanical breakers which arc badly if opened under load, and there are fast semiconductor breakers which don't arc because they simply change the resistance of the semiconductor. However, the semiconductor breakers have a problem that they generate resistance during operation. You can't get them down to negligible resistance, so they are constantly generating heat. A mechanical breaker, when conducting, is basically a large wire. It's resistance is very low, so very little heat.
The hybrid approach is to have both switches in parallel. In the normal conducting state, the mechanical switches are closed and the semiconductor switch is open. This means all of the power runs through the mechanical switches, keeping the channeler... I mean conductors cool. When a fault occurs, the system first closes the fast semiconductor switch, so that both switches are conveying current in parallel. Now the mechanical switches open. Because the semiconductor is conducting current around them, there's virtually no voltage across them, and thus they don't arc much at all. Now the semiconductor is conducting all the energy, and heating up like crazy. But it can then be switched open without an arc, and the current is fully interrupted.
This mechanism brings the best of both worlds. When everything is going properly, the mechanical switches conduct the current without generating heat. When everything goes wrong, the semiconductor switch can handle the load just long enough to let the mechanical switches disengage. It strikes me that your channelers would want to be trained in some art which mirrors these hybrid switches, so they aren't cooked to death!
Incidentally, my original answer was going to be relating limit of 9 mages to this idea of only doing reversible things so that you don't cook while using Ogone. In mathematics, quasigroups and loops are structures which have this reversible property. Anything which can be done in a quasigroup or a loop can be undone. This makes these actions reversible, and thus there is always a way to keep the energy flowing as magic rather than as heat.
Loops are interesting structures in that they have an identity element. It's possible to be in a state where you simply don't change anything. You let it be what it is. This seems like a really useful property for spellcasting. If things are getting dicey, you really want to have the ability to pause and just let things be as they are while you girdle your loins. If you just have a quasigroup, there's no such way to just let things be. You always have to know what you are doing to be able to keep things stable.
We know how many quasigroups and loops there are for different sized structures. For small orders (i.e. small numbers of mages), there are very few of them, and most are full fledged loops. But as the order goes up, the numbers get messy:
order quasigroups loops % quasigroups that are loops
----- ----------- ----- ----------------------------
0 1 0 0%
1 1 1 100%
2 1 1 100%
3 5 1 20%
4 35 2 5.7%
5 1,411 6 0.42%
6 1,130,531 109 0.0096%
7 12,198,455,835 23,746 0.000194%
8 2.69e15 106,228,849 0.00000039%
9 ≈1.52e22 9,365,022,303,540 0.0000000061%
10 ≈2.75e30 ≈2.08e19 0.000000000076%
11 ≈1.94e40 ≈1.476e27 0.000000000000000000000000000000000075%
This could be a part of why the circle tops out at 9 mages. If something goes wrong, the casters in the circle need to operate in a reversible way to make sure they don't turn into crispy critters. If something goes wrong, and you have to regain control, you'll regain control into one of these patterns. 9 elements is already a gargantuan number of possibilities. If you can't rely on everyone to agree on a particular pattern when they get spooked by the Orgone getting loose, you have to rely on taming the beast after the pattern has been decided. There's just too many 10 element patterns. Worse, most of them aren't loops, meaning you have a very high risk of a pattern emerging that is merely a quasigroup, meaning you can't slow the casting down. It's gotten out of control.
Maybe its just my love of mathematical flavor, but I found it interesting that this sort of pattern crops up.