Hello, did you try to use 2 lines in debian/watch ? It may work as you want
version=4 opts=pgpsigurlmangle=s/$/.sig/ https://download.kde.org/stable/applications/([\d.]+)/src/@PACKAGE@-([\d.]+)\.tar\.xz opts=pgpsigurlmangle=s/$/.sig/ https://download.kde.org/unstable/applications/([\d.]+)/src/@PACKAGE@-([\d.]+)\.tar\.xz
