What is a good ratio (range) of nut flour in Mandelkipferl dough?

Note that Vanillekipferl use almonds or other nuts - so Mandelkipferl would be a specific kind of (Vanille)Kipferl. They are dusted with or rolled in a mixture of confectioners sugar and vanilla (vanilla sugar or scraped/ground bean, not liquid extract) while warm. The term "Kipferl" denotes a crescent-shaped bakeware, in this case a traditional Christmas cookie from the Austrian and German cuisine.

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After checking multiple sources, amongst them Luise Haarer: Kochen und Backen nach Grundrezepten¹, the 1:2:3 (by weight!) approach for Vanillekipferl seems about right:

1 part (confectioners)/ sugar
2 parts butter
3 parts (flour and ground nuts combined) minus a bit

The highest ratio of ground nuts² (sources vary whether almonds should be peeled or not, other nuts are also possible) I found in my trusted sources is around 1/3 ground nuts and 2/3 flour. Many recipes use less. Note that the flour/nut part is usually, but not always slightly less than a full three parts (more like 2.8 or 2.9 parts) for the shortcrust pastry listed above.

I found one quote that vaguely claimed equal parts of nuts and flours as good ratio, but without giving a recipe. As I couldn't verify this with other sources, I'm questioning the feasibility.

Now note that to accieve the full crumbly mouthfeel of the "Kipferl", the pastry is made without egg³ and the "Kipferl" shaped by hand out of little lumps of dough. Chilling them again before baking is optional, but I usually do it.
Rolling the dough and using a cookie cutter requires careful resting, chilling and handling of the dough which may lead to overworking, especially if scraps are re-rolled. The ground nuts cause less stability than a flour only dough and can cause crumbling during the cutting.

Adding up to three yolk per 300g flour/nuts leads to a more pliable dough and many recipes for Kipferl recommend this. Still they often suggest shaping the cookies by hand.

Luise Haarer gives a very similar recipe explicitly for cutout cookies with the same ingredients, but one egg and a slightly skewed ratio, here the pastry consists of:

250g butter
200g sugar
125g ground almonds
450g flour
1 egg

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¹ German cook book that was in use for decades in schools in SW Germany. My trusted source for "basic" recipes and techniques. First edition from 1932, now (2015) 32th edition in print.

² Note that I use the term "ground nuts / almonds", not "nut flour", which is ambiguous and can mean either "(very finely) ground nuts" or "the leftovers from extracting oil from the kernels". While the latter is a common ingredient in gluten-free baking, we want the former for our cookies.

³ The choice of nuts and the egg / no egg Kipferl is much debated in many households in Germany and Austria. Just like with many recipes the quest for the "right" version may resemble a religious dispute. Do not get involved, unless you mean it. ^_^ Apparently the oldest written Vanillekipferl recipe was egg-less. (in German).

Someone who really is devoted to the Vanillekipferl and made a very elaborate website (in German, sorry), is Reiner Bernhardt, a professional baker.