Oh, and I re-read your post and saw “Unique Id”! That led me to try this:
The result there is that every field within the field editor gets a red label without specifying the class on each individual field. That may be more what you are looking for. But it is the CSS Class property, not the Unique Id that affects it.
But while I’m mansplaining, I’ll mention that you could match the Unique Id to the css. Leave the Unique Id as is (sk-1Sn1-459 in my sample) and change the resource code to:
#sk-1Sn1-459 .nx-basicfieldeditor-item-label { width: 20%; color: red; }
or change the Unique Id property to spouseInfo and the resource code to #spouseInfo ...
Maybe you needed a # instead of a . in your code!
