Hello James. You say these are experiments, so I hope you won't mind a few suggestions. Not sure why you rated FP4 at 200 in this high-contrast situation. But this may be why you have lost the shadow detail.
Also not sure why you gave "normal" development.
My own approach would have been to rate the film at 64, then give reduced development, to tame the high contrast. ID11 at 1+2 for 12 minutes at 20 degrees C. This would have resulted in more shadow detail. And the dilute developer would have given a compensating effect and, among other things, lifted the values of the mid-tones, resulting in a brighter, more airy, effect. You get this in spades with FP4 and dilute ID11. Pyrocat HD gives an identical effect.
Hope you won't take this as criticism...
Alan