An XML name (which is what is in between "<" and ">") has to start with a letter, an underscore or a colon, followed by other characters that can also contain digits and a few more special characters. Because your field name starts with a number, it is not a valid XML name, and therefore Acrobat had to come up with a method to still create a valid XML construct.
I don't know what "funky" character you are referring to. To me it looks like a line feed, do you see something different?