Next step is to help, simply by testing and reporting or if you feel wild, you could ask John a login to opt in our Rocket Chat instance and see how you can do more.
Yup. Just PM me.
But staying on v9, which is seriously outdated, just to use an even more outdated webmail system, is asking for trouble.
I believe RoundCube is already available in v10. Upgrade, and use it. And test Sogo if Brian manages to get it working. But you could be waiting a long time..... Don't wait for it to upgrade to v10.