A couple of things I noticed while looking at the package.
<file name="THEMEDIR/languages/english/ManageSettings.english.php">
should really be:
<file name="LANGUAGEDIR/ManageSettings.english.php">
ManageSettings.english-utf8.php doesn't exists in ElkArte because there is no support for non-UTF8 charsets, so the "-utf8" has been stripped.
This is related to SMF instead: you should never mix UTF8 and non-UTF8 charsets modifications in the same file. You should always have one file for each charset (not for language, but some language use different charsets).
And not necessary, but probably "nice" (as in less typing lol):
<file name="SOURCEDIR/admin/Admin.controller.php">
could be:
<file name="ADMINDIR/Admin.controller.php">