unfortunatelly it is not possible or I don’t know how I should do this in a custom design. I can add text into a custom design with variables but I want to do it through the standard invoice terms.
I tried this on a few setups also with the standard templates. Unfortunately it is not working on my side. I also tried it with only the variable in the field.
I will now manage with specific template for each use case (invoice, offer, …)