I believe there is an AP giving detailed instructions on log-book completion, but I have never seen it.
The inside front cover gives some guidance, and states of the spare columns that they are for "use as directed by Commanders in Chief or Air Officers Commanding ...". I think that puts them beyond "local commanders" juristiction somewhat!
By the way, if you are non-pilot aircrew do you expect sympathy from those of us who have to wrestle with the 14 columns of numbers?