No, and we won’t allow free-text matching on the value of a variable in CSL.
The current solution for most styles is to simply test for the presence of
a volume number or page range for journal articles, and in the absence of
both treat articles as published ahead of print, potentially testing for a
DOI to distinguish them from forthcoming works. That’s the easiest solution
and has the advantage that it works already.
Option number two is two simply print Status, but that’s tricky. We are
doing that for articles without a date with a status in some styles. Also
possible right now.
Option three would be to require restricted vocabulary for status (the way
we do e.g. for creator or locator types, i.e. likely via dropdown menu in
GUI implementations). That likely is the cleanest solution, but it’d be a
lot of effort and it’d require significant changes not just in the specs,
but also in GUI implementations.