Metatag has just released v1.12 which has some more i18n fixes after the big push in v1.9. Release notes can be found here:
Our current makefile as of WxT 4.4 in wetkit_metatag module is:
projects[metatag][version] = 1.11 projects[metatag][subdir] = contrib projects[metatag][patch] = http://drupal.org/files/issues/metatag-n2644742-3.patch projects[metatag][patch] = http://drupal.org/files/issues/metatag_html_entities-2648494-2.patch projects[metatag][patch] = http://drupal.org/files/issues/metatag-n2658262-6.patch
So we have already have the panels variable scoping fix and the fix for hook_metatag_delete.
The only patch of note we don't have in WxT 4.4 release is:
This is a bug where i18n_string when the site's default language is not the same as the i18n source language can cause translation issues.
Our next release (WxT 5.5) will have this fix but as we just released 4.4 it might take a 2-3 weeks. Just documenting this for clarity on the changelog.