I think it’s the other way - 20 dyne at 10Hz is moderately high compliance. 20 @ 100Hz is super high compliance.
Kiseki’s business side is Netherlands, so there’s at least a good chance it’s Euro 10Hz spec. I can’t see a 20 dyne @ 100Hz MC cartridge being a good choice. Hard to trust any purported information on such an old cartridge anyways.
The 8Hz - 12Hz window isn’t gospel. I’ve had good results with Koetsu RSP on lower mass arms like Graham Phantom (14g) and even VPI 3D Reference arm w/ dual pivot (11g?). I like them best on Fidelity Research (best bass & dynamics, more vivid crisp sound) but they’re still phenomenal on those other 2 arms. They like stability (gimbal, magna-glide or dual pivot mod) and you need to ensure a good sonic pairing with the arm materials, which is not easy to quantify. I had bad results with Jade on Clearaudio Universal 12" - I suspect the carbon fiber wand is not a good match. I’ve never liked carbon fiber in my analog chain, as it turns out.
You can go a bit below 8Hz especially if your turntable and isolation are top notch. If you’re too far above 12Hz and find audible bass response is affected, you can always add mass at the headshell.