I believe that the problem that is giving in CHMM2 is that it is not being able to modify the Themes. If the problem is this do these procedures.
Access the settings panel, then go to the option to uninstall 3DS applications. Perform the uninstall of the themes application, as you used the Freeshop to download the official themes package should have two theme files.Then perform this procedure, turn on Wi-Fi and go to the theme store in online mode, wait for it to create the files. Then go back to the theme gallery and install a colorful theme. Then go to CHMM2 and try installing a theme.
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I already had this problem that you are facing, I just do not know if this procedure will work for you. The error happened because the theme file gets too large and CHMM2 can not modify the data.