Hello,
1) Try to edit page now. I have increased SubstituteMaxLineLength limit in your .htaccess file and it fixed the issue with the page editing and Customizer.
2) Probably you activated theme on another domain or moved from localhost. Check this topic and follow solution described there https://www.8theme.com/topic/the-package-could-not-be-installed-pclzip_err_bad_format-10-unable-to-find-2/
Regards