can butter be substituted for margarine? salted or unsalted?

I second the use of butter. I have a lot of recipes from my mother that call for margarine or “oleo,” as it was probably called in the 1960s (or maybe that was just my mother). I’ve used butter in place with no problem.

I would not hesitate to use butter instead of margarine, Margarine has a higher water content.
When you think about it. Pizzelles have been around way longer than margarine. Unsalted butter will give more consistent results because salted butter is quite variable from brand to brand.