This report does not look optimistic.
All habitat patches have poor viability 'without frequent supplementation of animals' (Where all these leopards should come from? Possibly protecting corridors of semi-natural habitat is possible, and maybe Javan leopards can partially disperse through the farmland?).
Zoo population of 41 is mostly kept singly, and only 3 males produced offspring. The team seems to prefer 'short-term rehabilitation' and states that 'females have important role in the wild'. How the insurance population can appear, then?
The only optimistic part seems that something is being done, but, I am afraid, in few years when the project comes to practical solutions and action there may be no Javan leopards left to protect.