ingredient amounts given as intervals are not treated properly

[mkaut]

In many recipes, amounts of some ingredients are specified as an interval, such as "4-5 eggs".
If I do this in the Cookbook, the upper bound is completely ignored, i.e., it shows as "4 eggs".
I tested this with both "-" and "–", the result is the same.

Even worse, if I use spaces around the dash ("4 - 5 eggs"), the "- 5" part is interpreted as part of the name of the ingredients, so if I ask for twice the number of portions, it would say "8 - 5 eggs".

Is this a bug, or is there some different way to specify imprecise amounts that I did not think of?