My bad i misremembered the sizes

The size of the bleeder valves was actually somewhere between 1/4 and 7/32, without any adapter fitting.
I appreciate the research tho man!
After spending hours trying the ice cube trick to no avail I ended up bleeding the RF from the flare nut fittings where the mini hard lines go into the caliper: Open flare nut, press pedal,
cleanflametrap brake stickā¢, close flare nut, release pedal, repeat. Now both front calipers seem to clamp down equally strong. (although the rears aren't great it should be enough to stop the car)
Mega pissed at Cardone for making their bleeder valves so stupidly tight that unscrewing rusted 43 year old ones seemed like a walk in the park.