At a glance that all looks fine. For what its worth, I'd suggest removing all the WALTER you pasted in from appendix 3, and only put the bit on p6/7.
It certainly
smells like you've got a folder/file error going on. If you're editing the wrong file, or editing the file that's inside a different folder than the one the theme is pointing at, then its not going to have any effect.
The errors you were having with whole section not working sounds more like a layout termination cockup (do it myself all the time), though the code you've posted looks fine. Lets say you had:
Code:
Layout "1"
blah blah
EndLayout
Layout "2"
blah blah
EndLayout
and you put in one semicolon before an EndLayout
Code:
Layout "1"
blah blah
;EndLayout
Layout "2"
blah blah
EndLayout
...suddenly Layout 2 would be a child layout of Layout 1, and things would get very unexpected.
You're doing the right thing. Keep it simple, and start with the smallest amount of WALTER possible to learn each bit. Dubugging your own WALTER is tricky at first. Debugging how your edits have broken
someone else's WALTER is a bloody nightmare, because you'd need to completely understand how they were doing things in order to understand in what way you had broken it