A good article from thediplomat regarding the Australian submarine deal .
Although the author did not offer anything new, she did put all the political aspects of the deal in a very good chain of reasoning.
I believe, as she pointed out, a military acquisition of such scale is more political than technical and financial. All offers have pro and cons, not much dramatic advantage one over another. So if we stand a bit higher, the political consideration (mostly local job, maintenance, competence,
self sustainability during a real military confrontation) becomes dominant.
Regarding the quality of local work share, it is truly a reasonable concern, but that is the reality on the ground, a business man has to do something about it instead of snubbing the customer.
Regarding the possible cost overrun, there is no doubt it will, most of such military program does, F-35 is a good example where most of its delay and cost overrun is caused by domestic supplier LM. On this account, none of Japan or Germany and France can avoid it, but the deal is here, take it or leave it. And I believe, the Australian government and DNCS/France is aware and prepared for the overrun because at the end of the day weapon is for war which is 100% political, one pay whatever cost to fight.
The author dismissed the notion by many of China factor, I totally agree with her. On the other hand in regards of "self sustainability" in a pure military perspective, no sane military leader would have his weapon's cache or factory closer to the front line than his troops (in case Australia is forced to confront China). That may be a very tiny possibility or impossibility as neither China nor Australia want that, but a serious politician and military lead will never rely on (im)possibilities.
This brought my conclusion that "local production or maintenance" is a MUST that Japan failed to meet but France succeeded and probably the deciding factor.