The chapter 26.3.2 statement is that bringSiteOnline() need to be invoked for all nodes. This is not (longer) correct, it need to be invoked for all caches.

The new GlobalXSiteAdminOperations component will do this at once.

Another thing is that the bringStiteOnline() will only enable the repl, but not do a full update so only new put's will go to the other site.
pushState(site) will bring the site online and transfer the state.

Also the wording could be confusion, sometimes it is mentioned to invoke the method on master and sometimes on backup.
It should be clear that the invocation is needed on the current active site - the site which contain the up-to-date caches - otherwise the result is that the correct site is overriden with the outdated caches!