With 1200V and 1.5 A, it implies an impedance of 800 ohms operating somewhere. Do the capacitors serve as a matching impedance? Or are they the source of this impedance? I'm not sure.
If it were DC, the balancing resistors would be able to equalize the charge on the caps eventually, regardless of the cap values, and regardless of the variation between them.
In the case of AC, you will select a low enough value for the balancing resistors, so the RC time constant is able to have some effect during a cycle. The ohm value should not be so low that it discharges the capacitors more than a few percent during a cycle.
So if the smallest cap is 80 percent of the largest cap, then it may charge to a voltage 20 percent greater than the largest cap. And then if the resistor value is selected to discharge the smallest cap 20 percent during a cycle, then that may be sufficient for the resistors to do their job of equalizing all charges.
This is only supposition, because obviously the waveform in the antenna makes a lot of difference in the action of the balancing resistors..