It's hard to judge. The picture shows flowers with withered petals. It also happens to me with some tomatoes, but when I carefully remove the dried parts, I can see that there is already a small fruit inside. I don't see any withered flower stalks. If you have the temperatures as you state, then I think they are optimal for pollination. The hitch may be that there is no plant movement to aid pollination. Then you need to shake the plant from time to time.
Vladimír
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