Fortunately, the mailing list has been archived by MARC: Mailing list ARChives. The development mailing list is also archived here.
I had a bunch of recipes for KDE4 (and then 5, if I’m not mistaken), but Qt5 was a PITA to compile when alternative installation paths were used: several files had to be patched after
make install to allow programs attempting to link against libqt to find libraries and template files.
Last time I had to deal with Qt5 I just downloaded the binary package from their website and used it, but I didn’t give Qt5 a second chance.
I had a helper script to assist me on the automation of creating new versions of the KDE recipes. There’s still a copy of that (now deleted) script here, but I note that it uses deprecated Compile features like
meta-recipes, for instance, so I don’t know how helpful it’s going to be.
Best of luck