Didn't Buffy lose those powers a while ago?
We're not even talking about Cannonball here.
Clearly you failed to understand what was being said. I will simplify; Travel Speed =/= Combat Reaction
What are you on about?
These were examples. Cannonball has high travel speed and almost no reaction speed. DBZ characters, like Goku, have high combat reaction times, but have far slower Travel Speeds in comparison. Another example is Vampire Hunter D. He has upwards of around Lightspeed to low FTL reaction at best. His Running/Travel speed isn't anything remotely in the same category.
The best Reaction you showed for Buffy was outpacing and reading the writing on a bullet. That's low super-sonic. Ichigo was demonstrating hypersonic combat reaction in Soul Society Arc as Bankai.
Vegeta begs to differ. 2:06sec start.
Does that look like a plateau in the second page? No.