There wasn't really any commitment from the conference to continue the conversations about CTA anywhere specific... just lots of interest in doing so, since so many people now realise the need to unite on these larger issues.
I am chasing up various people in both the Hylo CTA groups and the Loomio "Open App Ecosystem" groups with a view to re-kindling the conversations... and will report back on any progress and the best way to get involved in ongoing discussions.
There is definitely some overlap between CTA and Nathan's IoO Directory https://ioo.coop/ which you linked to above, but to me they have different goals: The IoO aims to provide a directory of platforms and co-ops (and some platform co-ops!) but the CTA is a bigger mission: To network together the various groups working on overlapping "collaborative economy" software / technology projects.
I think this statement should act as the starting point for groups who wish to join the CTA, and use the seal:
"Adopting the seal is an explicit pledge towards interoperability between our technologies and our communities"
At least that would be a first step towards uniting the various communities. Then, once that has some traction, the CTA as a group of groups and individuals could decide what to do next and how.