See e.g. https://vital-signs.wmflabs.org/#projects=all,enwiki,eswiki/metrics=RollingActiveEditor where the "All Languages" option just doesn't show anything. Pre-SUL this was impossible, but now it's merely hard. :-)
@Jdforrester-WMF Closing this ticket, consensus among research team is not to use rolling metrics but there are many other metrics available in wikistats 2.0, please take a look for all projects: https://stats.wikimedia.org/v2/#/all-projects
And, as an example of a specific project, spanish wikipedia: https://stats.wikimedia.org/v2/#/es.wikipedia.org
We will be anouncing the site at some point tomorrow on e-mail first and on social and others later.
Please note that not all metrics can be computed for all projects but many can be so.