Chrysals have the potential to decrease breakage, not increase it.
Chrysals are in fact broken wood. Maybe the broken spots decrease stress in the rest of the belly but the bow is broken and on its way to folding where the chrysals are.
Sharpend they're both nouns.
"Following the string" is the older term, back when people probably didn't care a whole lot about reflex or whether somebody on the internet was going to be critical of their tillering job.
Nobody on this forum is going to settle the meaning of these terms with any amount of discussion, since 99% of the bowyers out there ain't reading this. And TBB wasn't written under divine inspiration, whether Bible is part of the title or not. If you want to distinguish between subtle differences in descriptions, you might just use the words to say exactly what you mean. In the case of just-unstrung set vs what you get when the bow has time to recover, you can use those words. Its already been stated which one of those is of practical significance, and which one is cosmetic.
One more observation that speaks somewhat to the original question. Shooting a well-made wood bow leads to set. Thats why the Thompsons went through multiple bows when they shot daily. If you rarely shoot a bow it will never wear out. If you shoot an overbuilt bow it will show little set, but will be sluggish. The former is a sad result of us having stupid jobs, the latter is to be avoided.