It is just natural that in #Ghidra #Sleigh “The [operand] identifier must appear in the [bit pattern section] as if it were a term in a sequence of constraints but without the operator and right-hand side of the constraint.”, see section 7.4.3:

https://scrapco.de/ghidra_docs/GhidraDocs/languages/html/sleigh_constructors.html

But it seems, you can’t use the identifier in the display of the instruction if it’s part of a constraint.

Error: “wrong type (should be family) in pattern equation”

Why is that?!

(Workaround: define an alias token for the same bits and use that in display)