Damn...I was hoping to come back and this riddle would be solved.

I don't have any ideas, but you told me to give the reasonings for my answers, and maybe you could give a hint based off them, so here they are:

The Heliotrope bounty - A heliotrope is a type of flower, or refers to the purple-ish color of that flower; and a bounty is either something plentiful, or something sought after. So the best I figure this line is talking about Aeris.
Following tragedy most final - I figure this line ties in with the previous, but tragedies and Aeris pretty much go hand-in-hand, so I haven't really narrowed down which tragedy this could be referring to.
Descent gains potency - At first I thought of descent as downward motion, but I'm starting to think it's used in terms of ancestry, which again could be referring to Aeris, or, for a change of pace, Sephiroth.
Ascend on with the great chronicle - No idea.