I had a tread about the same subject, first and id of the plant that i had, which here people said is decaisneana, then about pollination.
My vine got huje this year, had quite a few blooms which i self pollinated at first but seeing that nothing ever sets i just quit to mess with them. In my tread people said that it can be pollinated with caerullea pollen, couldn't try that as my caeruleas were heavily neglected so didnt had blooms at the time.
The plant didnt set anything ,second year its blooming heavily for me in the gh. There was one flower that kinda had a more swollen ovary but also didnt set. It awlays blooms in september, just when we start getting cooler temps over-all. I really dont know if this is the reson it doesnt set, or its just not self compatible, or just needs time.....
The flowers u show are really just too fresh after the bloom to be judged for pollination. With edulis the ovaries start getting bigger right after pollination, dunno the growth pattern on decaisneana fruit set as mine never had any. I can tell u that after 2-3 days whats not pollinated will start getting yellower and start to wrinckle a bit. When the actual flower parts start to dessicate, thats the time u can judje if its pollinated, if the ovary stais green and gains some size, its succesful, again judjing by my purple edulis.