It is not non sense. I am spaniard myself and I did not understood what he was talking about until I saw the correction(is this a club name or something?).

If I want to talk about "Seattle" and use "Siadol" a lot of people are not going to understand.

"Saragossa" is an old and well-established spelling of that city's name in English and this is an English-speaking forum

A name is what something is called. For people it's rude to call them by a name they didn't choose but for non-persons that doesn't matter, if everybody else wants to call it "Siadol" then that is its name.

Every language has his own name for tons of places. In Spanish it's Zaragoza and in English "Saragossa". Ditto with Londres/London.

At least you learned something new today