Red: I understand how it is, because I had a hard time comprehending "semi-determinate" due to the plethora of definitions or attempted explanations that exist online for semi-determinate ... often conflicting.
And the more words I try to use in my explanation of semi-determinate and semi-indeterminate, the more I risk confusion as well.
Let me cut to the chase: All determinates and semi-determinates eventually terminate all forward growth with an efflorescence. All indeterminates and semi-indeterminates eventually terminate foward growth by disease, frost, predation, mechanical destruction, etc., and not due to terminal efflorescences.
Then the distinctions between det., semi-det or between indet. and semi-indet. are the patterns of efflorescences relative to the internode spacing.
Also, I see you did notice what I said about the MoCross semi-indeterminate ... that there were frequent and in-pattern efflorescences right on the node rather than in the internodal stem segments. Yes, I found that promotes higher production, far better production in fact.
Anyway, here is a pdf that may help explain how one group of horticultural scientists defined semi-determinate:
http://hortsci.ashspublications.org/.../1074.full.pdf