Thanks. The problem of the blog post is IMHO that it's unclear what audience it's directed to. The learnings and suggestions *might* be useful for some en.wiki WikiProjects, but en.wiki is obviously the least suitable wiki for such experiments. There are no learnings for other projects and I see no answer e.g. to questions I had for a similar fr.wiki banner a few weeks later. https://meta.wikimedia.org/w/index.php?title=Meta%3ARequests_for_help_from_a_sysop_or_bureaucrat&diff=5337142&oldid=5337118 It will be for next time then. :)
Nemo
P.s.: It's not particularly surprising, I see that I had already predicted this failure. https://meta.wikimedia.org/w/index.php?title=Talk:CentralNotice/Calendar&oldid=5337147#Philippines_recruitment_for_two_weeks