Bug#827823:

The Cmake variable @KWIN_WAYLAND_BIN_PATH@ in the script is not correctly replaced as it should be.

However, it correctly defined there:
https://sources.debian.net/src/kwin/4:5.6.4-3/KWinDBusInterfaceConfig.cmake.in/

in 5.6 KWin dependencies.

During building, I see that this package was built with old 5.4 kwin dependencies which seems odd

Get:541 http://ftp.us.debian.org/debian unstable/main arm64 kwin-data all 4:5.4.3-1.1 [2815 kB]
Get:542 http://ftp.us.debian.org/debian unstable/main arm64 libkwinxrenderutils6 arm64 4:5.4.3-1.1 [16.4 kB]
Get:543 http://ftp.us.debian.org/debian unstable/main arm64 libkwineffects6 arm64 4:5.4.3-1.1 [59.8 kB]
Get:558 http://ftp.us.debian.org/debian unstable/main arm64 libkwinglutils6 arm64 4:5.4.3-1.1 [69.0 kB]
Get:559 http://ftp.us.debian.org/debian unstable/main arm64 libkwin4-effect-builtins1 arm64 4:5.4.3-1.1 [230 kB]
Get:562 http://ftp.us.debian.org/debian unstable/main arm64 kwin-common arm64 4:5.4.3-1.1 [1159 kB]
Get:568 http://ftp.us.debian.org/debian unstable/main arm64 kwin-dev arm64 4:5.4.3-1.1 [48.6 kB]

at https://buildd.debian.org/status/fetch.php?pkg=plasma-workspace&arch=arm64&ver=4%3A5.6.4-2&stamp=1464722064

And of course, in 5.4 KWin depencies, there is no @KWIN_WAYLAND_BIN_PATH@ cmake variable replacement.
cf. https://github.com/KDE/kwin/blob/Plasma/5.4/KWinDBusInterfaceConfig.cmake.in

The solution seems simple to me, this package needs to be rebuilt with up-to-date KWin depencies now already present in testing/sid repositories.

Regards,

Samuel