Hello Sandra.
I've noticed two things in the translation, both in the installer.
1) When upgrading a previously installed version, the first install option says "Salir" (Quit) instead of "Typical"(TÃpica) or something like that.
2) In the license agreement page, the "I Agree" and "I don't agree" labels are mixed up. I had to choose "I don't agree" in order to install the program!
That's all. Bye!
ps. I remember a long time ago there was a Paint.NET Spanish translation available.