An interwiki search which return results on another project which are not in the main namespace, use the canonical namespace, which is wrong for that language. So in the URL it should have 'Ayuda' instead of 'Help'.
Note that since groups are joined by language, it could use the local translation for that namespace, except for NS_PROJECT (NS_PROJECT_TALK). The value of wgMetaNamespace would need to be fetched from SiteConf.
Results from extra namespaces don't present this issue, they have the right namespace name.
Related to bug 15452 ?