Would be fun make the same recipes from different editions and compare. I've noticed some minor variations between my parent's copy and mine but neither are really old.

I remember my ANZAC biscuits recipe in particular has less butter and more sugar, like you say, and is clearly inferior. A bit sad. However we also have Edmonds: Best of Baking, which is newer than my Edmonds Cookbook, and prescribes more like the old recipe with more butter.