And that appendix would just say, “Read the Results pane when you try to compile and follow its advice”?
With regard to the Consolidated Multiple Actions extension, it did have some outdated I7 grammar issues, so I went through and fixed those, which let me get far enough to see the multiple I6 errors it was throwing, at least.
There have been some renamed constants and functions in the latest I6 update that accompanied I7 6L38, as (partially) documented here, and Consolidated Multiple Actions relies pretty heavily on some I6 includes. I did try renaming the extension’s references to these changed constants and functions, which fixed those errors, but only let me get as far revealing different I6 errors. So my point is that Consolidated Multiple Actions is essentially a lost cause unless the original author, or someone a lot more competent with I6 than I am, wants to update it.
My broader point is that the Handbook’s target audience probably mostly consists of people who don’t want to tinker with I6 code in the first place, and that fixing out-of-date I7 grammar tokens is usually as easy as reading the Results pane, so I just don’t see what the big deal is. My even broader point is that outside of a core few authors, I7’s extension authors have not been doing a great job of maintaining their extensions.
EDIT: Well, in fairness, as far as out-of-date I7 grammar goes, having a handy in-one-place reference, eg “You used to say [this], now you have to say [that]” would be pretty cool.