Because
@JackCY owns an R34, I would be open to a further discussion. I never saw this brake-oversteer as a particular issue: more-so an inherent feature of the open differential and overall suspension balance. Actually there are some scenarios where more brake oversteer is clearly needed.
I have some basis for it as well:
For example here at 4:02, and various other sections, pay mind to the attitude of the car and the fashion and amount of brake application:
Or 4:20 where a mere lift of the throttle fully unsettles the rear. Or 5:20 where a mere tap of the brake unsettles the rear fully. Moreover none of my testers ever reported any instability on brakes, on R32 or R33. My R33 tester also owned an A-LSD, so it was open on coast.
Also here in this video, at 21:25 is something that stands out to me.
Notice the need to countersteer after braking, in a stock R33 V-spec. The BeeR car in the front probably has a rollbar and/or brake bias issue, but that is not to be used as reference.
22:10 as well. This appears excessive, no? But there it is.
Due to factors like this, I never really considered it an issue, mainly because the inputs matched up well. It's very well possible I'm driving around it and not paying attention to the issue. It does feel like there is too much rear looseness on brake application, if I would consider how I would set up the balance. So I'm keeping an open mind. I tried a lot of things and nothing worked: so do try your own if you wish and post the results.
PS: The R33 has almost identical suspension to the R34, and identical brakes. So I believe it's a sound reference. And the 33 is considered more stable than the 34, with more understeer...
EDIT:
Why not, have some more. Although too unclear to use as reference.
At 7:12 onward. Also 7:50 onward. Also 8:15 onward. The only place it seems where R34 doesn't oversteer on brakes is low speed, high front-slip scenarios.