In order to use "/dada" subpages to hold the template data tags for each template, I tried[1] to add a link like "data" to [[MediaWiki:Templatedata-doc-params]] but I got the following HTML:
<caption>Template parameters <a href="/w/index.php?title=/data&amp;action=edit&amp;redlink=1" class="new" title="/data (page does not exist)">data</a></caption>
meaning the link was not functional.
Version: unspecified
Severity: enhancement
I'd argue this is by design. The message is supposed to contain plain text only. I don't want unicorns or templates to be invoked here.
It does apply message transformation so that anything required for proper localisation works (e.g. plural, grammar, etc.).
This is to keep the messages flexible and re-usable. And to allow them to be used on the client-side.
Per translatewiki guidelines or in MediaWiki message terminology, consider these messages format=text, not format=parse or format=wikitext.