In the Set node you can’t use “=” because that assigns a value and ends up changing the JSON behind it. What you want is a conditional expression. Just write:
{{ $json.propertyValue ? ‘Verdadero’ : ‘Falso’ }}
This way it only reads the value and outputs either “Verdadero” or “Falso.” If you need more complex logic, use a Code node instead.
I think it’s fine, you’re just assigning a new value to the same field propertyValue using = which will directly take effect..
What behavior are you expecting?