You can clone with
$ isutf8 locale/es-CL/greasemonkey.dtd
locale/es-CL/greasemonkey.dtd: line 27, char 1, byte offset 49: invalid UTF-8 code
See original discussion: https://groups.google.com/d/topic/greasemonkey-users/ZJo60moupDU/discussion
A mended copy of the above mentioned DTD file has been uploaded to Greasemonkey's es-CL locale folder at BabelZilla.org. The faulty character was replaced with its UTF-8 equivalent.
Updated translations from babelzilla.org.