Further analysis showed that from August 6th onwards(last deployment date), contenttranslation tags were not added to several articles published. For all such articles, while publishing, following error is reported

{"xhr":{"readyState":4,"responseText":"","status":200,"statusText":"OK"},"textStatus":"parsererror","exception":{}}

AFAIK, this indicate the api returned something that the jquery ajax could not parse. All of such articles was published, just that the tag is missing.

I saw only one instance of this error so far .

The title sounds scary, but it was indeed only once, then it's Normal prio. Should be raised if it happens more frequently.

Has this happened again? If it only happened once, I'm inclined to closing it or making the priority lowest.

Any slave lag spikes will cause this. Avoiding those is T95501.