At the top of $:/core/ui/Buttons/new-journal-here

\define journalButtonTags()
[[$(currentTiddlerTag)$]] $(journalTags)$
\end

This definition seems to set a current tiddler as one of multiple of the New Journal tiddler's (created upon pressing this button) tags. This may be a step towards letting me make a non-tagged (but maybe linked!) Journal Here button, which would help to curb the number of tags produced while merely considering multiple matters.