Error when value is an URL with an = symbol
Fragment of a discussion from Archive talk:Template format
Could the issue be that you need to a "1=" to the "convertir fecha" template call in that 2nd link?
I have added the '1=' and the result is the same, there are broken links.
If this is still a problem, can you log this as an issue here: http://semantic-mediawiki.org/wiki/Help:Reporting_bugs