Not impossible. How about a two stage bleeder system? At say 50 volts a second relay de-energizes and the NC contacts throw a smaller resistor across the cap bank to finish it off?
Your source of power. NC relays failed with a spring closing a set of contacts closed. Power opens them up. This follows standard fail-safe practices where Everthing not working results in the safe state. Same for cabinet interlock switches and safety pull/emergency stop loops. Opening the circuits, even through broken cables or connectors failing will stop the process.
DC operated relays and contactors tend to magnetize and have all sorts of hystersis curves with when they mechanically turn on vs. off, so thinking you can just pick some resistors and get a relay to turn off at a specific voltage can be tricky. AC coils for contactors are lossier and won't tend to magnetize so even though you'd be working off the data sheet, it may be easier to control when a coil really drops out.
you just need some resistance so you don't weld your contacts. 200 volts with a 10 amp relay = 20 ohms, which is a 4 second time constant. 10 amps is pretty wimpy as far as relays go too.
the 4800 watt second systems don't seem to leave the wake of destruction and kill as many people as you'd expect. The shut down process is to fire off the strobes, but this seems to have changed in the classic Speedotrons made in Chicago vs. the designs they're using after they were bought.
200 volts is too low to just dump into a flash tube, but there are triggeable gas discharge tubes out there. The classic SCR crowbar would be fun too, with a current limiting resistor sizes so you don't exceed the ripple current rating of the capacitor. Power SCRs are cheap, can have high current ratings and are very reliable.Camera strobes actually use a SCR and inductor crowbar (I think across the tube itself) to quench the arc in a flash tube to turn the power down. Low intensity flashes are actually just really short flashes of light. The capacitor is still always charged to the same voltage needed for a full power flash. You can hear the click of the current in the inductor in cheapo speedlights from the 70s and 80s marked "Thyristor".
I used to have a magneformer which ran at about 9kJ. It had sturdy energy dischage capacitors rated in the tens of thousands of amps, so it was fine to really just throw grounding wires across the terminals and switch when you were done. Rebound can be high on high voltage caps which is why they're always stored and shipped with a wire across the terminals.