This 3-23 vic, apparently uses 25 mA out of resonance, and then drops down to 1-2 mA, so not much power being sent through the core. Voltage is unknown, but from the control patent, a guess might be around 650 volts, with mentions of 2000 volts and 5000 volts...
One thing is for sure, if you look at the 5-coil-vic picture. It certainly didn't develop a very high voltage. I would say, at most about 2-3kV (which would match the values indicated in the patent for this kind of WFC). Why? If you look at the connectors to the cell on the right side, you see that the isolation plastic distance washers are not very thick. If a higher voltage would develop, there would be a spark to the casing. You would also get heavy corona discharges at higher voltages with these connectors. This is very different from the connectors of his 6-1 coil. There he really used High-Voltage connectors. And as far as i understood, these coils actually were meant to get in the xxkV regions.
This is actually IMHO quite interesting. As I have mentioned before, according to the Tay-Hee Han patent, you need at least an E-field of 20kv/mm for water to split just due to the E-field, and it is not possible to develop such a high e-field without having an isolator in between, because the water would arc through already before that. Therefore I personally think his effect is not really splitting the water molecules directly by an e-field, but rather separating the already available ions with an E-field and letting them again neutralize each other, whereas some will then build H2 and O2 instead of again H20. This would still be IMHO the only solution which would actually explain where the overunity splitting energy is coming from.
For ripping apart water directly just by an e-field is not an overunity reaction. Why? Because due to the splitting action, your e-field of the capacitor would loose energy. This is called losses in the dielectric of a capacitor.
So my all time changing guess

would be, that you really go to the point where you just would get a water arc. But due to the very small energy in the oscillator, the arc cannot really develop, but just the pre-arc-situation, where the ions get heavily separated. Then you immediately have to stop the oscillator (gating off), for otherwise you would again pump energy in it, and as soon as the ions didn't had time to neutralize, the ion conduction channel would still be there, and then you would get an arc, which would waste your energy just in heat. But just another lame hypotheses... I know...I should really stop with that and continue experimenting...