Why is "brazen" translated as "bronze"?

Question

In the English edition of "The Adventures of Huckleberry Finn" (at least the version available on gutenberg.org), this sentence appears:

"It's the brazen serpent in the wilderness!

The Spanish translation found elsewhere is:

«¡Es la serpiente de bronce del desierto!

If I'm not mistaken, a reverse translation would be, "It is the bronze serpent of the desert!"

Why is "brazen" translated as "bronze"?

Note: in actuality, the serpent on the pole (which was made when the Israelites were wandering in the desert) was said to be of copper, not bronze (see this for the details).

Answer 1

Brazen has multiple meanings in English. The most common is "bold", but a more archaic (and chiefly literary) secondary definition is "made of brass".

Answer 2

As pointed by @ukemi and according to the Cambridge Dictionary

brazen

Made of brass

brass translates into Spanish as latón, a different alloy from bronze although they both contain copper.

I think that probably the translator considered it a typo, that "branze" was really "bronze" and translated it accordingly to "bronce".