Spraying the radiator is extremely unlikely to do any damage. The main risk of high-pressure hoses is that they either force water past rubber seals into electrics or force it into sealed bearings.
I had to repair the ECU in a Ducati a few years ago after the dealer high-pressure washed it and water got inside the fully sealed unit
I can't think how this would cause a collant leak unless you damaged either the radiator cooling fan or temperature sensor, and the temperature overloaded when you were stationary.
Cheers,
Jason