The translations files are encoded in UTF-8, and yes, HTML entities should not be used. (UTF-8 is non-standard for Java resource bundles, but was necessary to support Chinese.)
Yes, the "add" option should not be displayed for non-admin. But the problem with copying (which non-admins can do) is that the user's (cached) permissions were not being refreshed after the copy, so the edit failed. In any case, both issues have been fixed for next release. Thanks for the report.