Rubin seems to have been maintaining x11-wm/lumina since Mar 2016. However, it seems that his commit activity ceased the same month, and his last Bugzilla comment was in May 2016. Rubin, are you still interested in maintaining this package?
Hi Michał. I'm not using Gentoo at the moment. I've not maintained this package actively and I think this could better be done by someone else or that the package should be obsoleted c.q. removed.
commit cc62e48abf5aaf04ded496bc8f7c6e0e8b65e39b Author: Jonas Stein <jstein@gentoo.org> Date: Tue Oct 3 15:24:34 2017 +0200 x11-wm/lumina: Removed proxied maintainer Removed proxied maintainer as requested in bug 632702.