In fact they did that before.
You may have seen coins with a "bin lira" denomination, like this one (image from gutefrage.net):
Well, that is a 250,000 lira piece; bin = thousand. (And those words that mean "new" do indeed go back to some common Indo-European root. In Europe you will find "non-n" words among the usual suspects, languages such as Finnish, Hungarian, or Basque.)
Brazil is a strange mix by the way. After a long period of Real coins, they introduced the Cruzeiro in 1942. That was replaced by the New Cruzeiro in 1967; three years later the word "New" was dropped. In 1986 the Cruzado came, followed by the New Cruzado three years later. As far as I know, these Cruzado Novo coins are the only ones that actually feature the word "novo".
(BCB/central bank image.) 1990, another Cruzeiro. 1993, the Cruzeiro Real, and (since 1994) the Real again.