You can probably use the HTML feature of the textinsert plugin.
For instance, you can define
current_user as:
<a href="/your_wiki/doku.php?id=#@USER@#" title="#@USER@#" class="wikilink1">#@USER@#</a>
Then you can refer to this in your text as
#@current_user@#[/m], which will give you an internal link. If the user's name is jack, you will get: jack. Notice, you will have to use [m]> for the closing angle bracket. Also, the link will always show up as a valid link, even if the file hasn't yet been created, because of the 'wikilink1'.
See:
plugin:textinsert, in particular for this case:
standard_namespace_macros