As an SEP can I please ask you very experienced pilots a question?
If you are flying an (any) aircraft with no outside vis. and suspect instruments and your body and altimeter gave every indication that you were hurtling downwards at a high ft/sec. would it not be a 'normal' reaction to pull back on the stick irrespective of any flight instrumentation. Could this therefore be a case where old fashioned 'seat of pants' reactions were the wrong ones and less 'flying' training and more 'flight' training might, in this case, have yielded a better outcome.