For the spekboom I was seeing many videos on YouTube of people cutting them all the way down like I did. I was focused on getting it to taper from bottom to top.
This plant is rarely used for bonsai as it's hard to create a convincing one. However, if you like it, go ahead. Just wait for it to start growing leaves again, give it sufficient time, be patient. However, don't try to create a mallsai - a commercial, cheap product, that isn't a beautiful tree, but a cheap looking copy, that needs stones, rocks, moss as decoration to make it look better than what it is.
For the rosemary, the main trunk has a definite S shape
A symmetrical S-shape is seen in mallsai and something you definitely don't want in bonsai.
I left the last set of leaves on each branch. Can you explain what I did to the rosemary that would kill it, and what I should have done differently?
Oh... good. Rosemary will not bud back. I didn't really see any foliage - and without foliage, it's essentially dead. So, for this one the same: leave it lone, give it time.
apologize if what I've done has offended you
You have not offended me in any way.