Anyway the original issue was this "I also doubt things in the Enneagram like an absence of a nitty gritty structure to determine why there are exactly 9 fears/desires"
I do get what you mean there, but my point is, it's the same issue with socionics/MBTI, why stop at X number of dichotomies. The same issue as to why there are 9 fears, why not more or less. Do you disagree and if so why?
Btw I kind of liked this for giving a structure to enneagram: link
And there was a Karen Horney article that also did add some structure to it... this one