For the issues at 1:12 AM, this looks like you were uploading files at 1:12 AM and caused those errors because the process took those files offline for a second.
As for your other issue...
With the CDN on, even while VaultWiki is disabled, large numbers of resources do not work for me (most images). Example:
cdn/styles/default/xenforo/gradients/form-button-white-25px.png
Returns "500 Origin Error: The origin server is not reachable or returns an error."
If your CDN was active while you were upgrading XenForo, this could cause the issue. It may have tried to refresh from the origin while the files were locked for uploading or while they were partially written. After all files have been completely uploaded, you should try changing your CDN expiry URL parameters. Right now it looks like the datestamp used for many images is from July 2017.
I was not able to reproduce the issue of not being able to post on your site currently, nor after enabling VaultWiki. However, I have re-disabled VaultWiki so you did not wonder how it magically enabled itself.
I believe that your issue was most likely caused by your CDN attempting to pull Javascript resources from the origin while you were still uploading those resources (and then caching that state in the CDN). You tend to have issues with users accessing resources while you are uploading them. Since you use a CDN and your site is high-traffic (so you cannot guarantee that users will not access the site while you are upgrading), you should make use of XenForo's cache-buster config.php option (which you currently do not).
In
library/config.php:
Code:
$config['jsVersion'] = 'random_string';
After every completed upgrade of XenForo (or any time you modify/upload Javascript), you should change this to a different random_string of your choosing. This will force the CDN to re-pull your Javascript.