No idea what other changes from 4.x there are so far, but the bigger
concern is that the 5.x docs will continue to diverge from it as time goes
on, making them less and less useful for 4.x work.
As far as I know, the current doc still applies to version 4.3. Only one
page, "Upgrading to ColdBox 5" that concerning version 5; and that is still
work-in-progress.
I know it's confusing. Ideally, the doc should not mention version 5 until
the framework is officially launched.