Right now, MediaWiki has no way to localize '1st', '2nd', '3rd', etc. The CLDR database includes rules for creating ordinal numbers but these rules are not currently extracted or utilized by the cldr extension.
The rules are ruleset type="digits-ordinal-indicator" in core/common/rbnf. Here is a sample for English:
<ruleset type="digits-ordinal-indicator" access="private">
<rbnfrule value="0">th;</rbnfrule> <rbnfrule value="1">st;</rbnfrule> <rbnfrule value="2">nd;</rbnfrule> <rbnfrule value="3">rd;</rbnfrule> <rbnfrule value="4">th;</rbnfrule> <rbnfrule value="20">→→;</rbnfrule> <rbnfrule value="100">→→;</rbnfrule>
</ruleset>
Version: unspecified
Severity: enhancement