So I got Bakir, Abd el-Mohsen. The Cairo Calendar No. 86637. (Cairo, 1966) from the library. Wow. So many festivals!
I found it interesting that on the First Day of First Akhet it lists a “Feast of Isis” along with a “Feast of Osiris” and a “Feast of Every God and Goddess” (page 11).
And I also found a Hatmehyt Festival listed. She can be syncretized or aspected with Aset. So, here is this information 4 Akhet Day 28: Procession of Hatmehyt in Busiris (page 29).
Going to go look at more festivals now. Shiny!