I don't know eibach's spring rate, but they're most likely going to be a bit higher than stock if they lower the car an inch or two. In my experience, the FSD's were already overpowered by the stock SS springs. Shorter higher rate springs would have been plain ridiculous. I'd caution you against that combo (unless you would like to buy my Fsd's off me!). The Yellows are what you need if you really want Koni, especially if your lowering. They seem to be an excellent all-rounder. I know of at least one member on JC's that uses, or did use Fsd's with lowered springs. Maybe they could chime in and give their thoughts. They may completely disagree with me and I'll be able to sell my Koni's with a clear conscience.
Eibachs for the VE are progressive rate, which I believe is the least aggressive spring compared to most other lowering springs, at least for the initial couple cm of travel.
As for the FSDs, I do believe they were valved for stock FE2 rates, but does a decent job with my setup probably because of the progressive rate of the Eibachs that works with the digressive valving, and I can definitely see them being under damped for other higher/linear rate lowering springs, even though they are by far closer to critically damped than the Sachs shortened shock I paired with the Eibach initially.
Regardless, from looking at some pictures, the only difference in the rear between VE and VF is the upper control arm? If that’s the case I don’t really see why VE and VF springs and dampers wouldn’t swap over for the rear, besides ride height/weight differences. Can someone please correct me if I’m wrong?