I think that you need to determine FIRST if Scripture calls Rosh Hashanah, Yom Kippur and Tabernacles "Fall Feasts" or not. As far as I can see, Leviticus 23 only designates the months and days that these feasts are to be observed. There is no mention of seasons. So, I am not sure what point you are trying to make with regard to the fact that some of these feasts are celebrated during the end of summer.
Three of the feasts of Leviticus 23 are clearly harvest based – Firstfruits, Pentecost and Tabernacles (for barley, wheat, and fruit, respectively). I will venture to say that particular harvests are consistent as to when they can be expected to occur in Israel. Furthermore, the timing of a harvest is not going to be affected by arguments that its designated harvest festival is one or two months off on a calendar. Rather, it is the timing of an actual harvest that will confirm the correct placement of its festival on the calendar.
Consequently, the grape harvest is not celebrated in the spring in Israel. Nor is the barley harvest celebrated in the fall.
But, with regard to your post on real or fake fall feasts, it should be enough that Scripture does not does not call any of the feasts of Leviticus 23 “Fall Feasts.” Thus, no violation to the Word of God will occur simply on the basis that Rosh Hashanah or Yom Kippur are scheduled a few weeks before the autumnal equinox.
– Lisa Taylor