
I read somewhere, that the ROSA Team is a little bit unhappy with the current Installer, afaik is it outdated ?
KaOS and some other Distributions build together a Qt 5 based Installer Framework, Kevin Kofler from Fedora add rpm support, Teo, a payed BlueSystems Developer from Netrunner maintain it. It support UEFI, multiple locales, automatic partitioning and so on.

http://calamares.github.io/about/