Hey Asbjørn,
Your web host does not have an error log so nothing will show us the exact cause. Please contact your web host to enable error logging in your site and tell them to monitor the fatal errors. This issue might be due to CPU usage being limited by your web host. Please ask them about that too.
Anyway, this issue only happens on your site. That means that your web host could not handle the combination of WPML, Cornerstone, and The Grid. Regretfully, the only sensible resolution for this case is to move to a different web host. Otherwise, we’ll continue going back and forth guessing what the cause is and the solution.
Thanks.