What about to just import the license, import the registry "HKLM\...\APPX...\Copper...something" and then copy that dir to WindowsApps?
LOL, you really like this Copper apps. I don't even have the DP ISO, removed long time ago. I think you said it failed to package the apps to appx, so it shouldn't be a problem with the license or registry values. Sometime when the Chinese tool failed to package some apps, I tried to do it manually following the MS instructions(it's somewhere in the Build blogs or technet blogs, couldn't remember), and failed too, I have very little VS knowledge, so couldn't go further. btw, guess I have not mentioned before, we could side-load the alarm and calculator to win8 RTM, but not the recorder and movie-moments .... I tried it with power-shell and the cause is obvious: these two apps require to work in kernel 6.3.