I don’t believe there is any actual standard for ‘ideal cut’ in Asschers/square emerald cut diamonds. Do you have an example of one you feel displays what you find to be a desirable appearance that you are trying to find?
Asschers are as unique as snowflakes. What style are you looking for? Wide or narrow windmills? Broad or narrow steps? A tiny table or a wider table? A square emerald, generic asscher, cut cornered square step cut or a branded cut like an Octavia or a Royal asscher?
The asscher in my avatar is a cut cornered square step cut. It has a high crown with a tiny table and more pavilion steps than the average square emerald cut. I chose it for the contrast patterns which are pleasing to me and its brightness. What aspects in an asscher do you like? There is a chart of ASETs for each shape of diamonds that you can google which shows good, excellent and poor quality ASETs.
Do you have a video or link to this asscher so we can see how the contrast patterns change when it is rotated?