Thanks everyone for the advice, if only to confirm that it was a difficult construction! Dhivan has also replied offline and I think John is on the right track. Dhivan says:
"When there is mindfulness and full attention, for one who is perfected in mindfulness and full attention, there is shame and moral dread which is endowed with a requisite"
'So I take both compounds ending in -sampanna as bahuvrihis, one gen. and one nom., agreeing with the predicate of the main clause (here hirottappa.m, neuter). How to translate -sampanna is always an issue, and here I use two English terms; I'm sure you'll have your own preference.'
This makes sense of it I think.
John. I'm doubtful about following Bhikkhu Bodhi's "proximate cause" for 'upanisaa' as there is some doubt about saying this is causation. It's a condition, rather than a cause. I've been using 'precondition' in my translations.
There does not seem to be any commentary on this term. But it is interesting because it applies the "imasmi.m sati ida.m hoti" locative-absolute construction to lokuttara pa.itcca-samuppaada. This suggests that they are not two different processes, but one with different applications. One that happens automatically and keeps us in sa.msaara, and the other that is invoked by practice (particularly morality) and sends us up and out of sa.msaara.