Hi,
Try to remove your favicon and set it again.
We also have just release a new version of cornerstone Version 3.3.1, which is the compatible version for your theme - X 6.3.1. Please update Cornerstone and check if it fixes the issue with your Spanish site.
Please always check changelog for version compatibility and latest release.
https://theme.co/changelog/
Remember to clear all caches when updating so that the code from the latest release is always in use. This will help you to avoid any potential errors.
If these doesn’t help, kindly provide us your wordpress admin login in Secure Note
Thanks