I think we’re dancing around each other here. What you suggested is precisely what I am doing - I got 2019 Golf R B6’s and am installing them with 2019 Golf R springs (inc R Estate rears). That’s because B6’s are OEM ride-height performance dampers, and I’m putting OEM springs on.But that's just it, you can't b/c the R B8 is going to be way too short b/c the R has shorter stock springs so the lowering springs are even shorter which may cause issues. The shorter damper going from 6 to 8 is simply for preload on teh spring at extension; the damper is exactly the same otherwise. It would make more sense when using R springs to lower an to use the R B6.
In the case of B8’s, they’re lowered performance dampers. So you would need an aftermarket lowering spring, no OEM VW spring will go low enough for them.
so if someone wanted to lower their Alltrack, and by lower I mean lower than Golf/GTI/Golf R, it would be smartest to do aftermarket springs and B8’s. I’m “lowering” my Alltrack on Golf R springs with B6’s but it’s still what I would describe as “OEM-lowered,” since the R springs are the lowest offered in the entire model range.