The speed of rotation and the orbit period are independent. If the days were shorter, there would have been more of them in a year but it would still take the same amount of time to circle the sun.
365 days in a year is just a rough approximation, some years there are 366. If the earth were spinning twice as fast, there would be would be more than 700 days in a year but the year would still the same length of time and you would age one year, not two or 1/2.
Stepping back from the purely religious aspect of the Biblical account, it’s fairly obvious that the flood account describes some sort of cataclysmic impact to me, to have “opened up the fountains of the great deep” as it was described. Such an impact could very well have altered the orbit of this planet, couldn’t it? The rate of spin could have been reduced as well. There are a number of ways this planet could have been flooded as described but it’s dismissed as impossible by people who know better. A large icy comet? There’s a possibility. I recall reading recently that there is a great deal more water contained within the crust of Earth and I believe under fairly high pressure, am I recalling this incorrectly? What would a large extraterrestrial object such as a comet or asteroid cause, in light of this, and how would an ancient have described it? As opening up the fountains of the great deep, maybe?
Maybe both the spin and the orbit were different.