With all due respect Chris, I'm not agree.
As you know on google everything is a problem, all things to be fixed if you want have a good site with a better ranking on own competitors.
The error is there to tell precisely one thing: Is there an error.
The fact that Google decide to show or not some contents, him does without to tell us that is there an error. Simply doesn't show in the search results. It show an error when something is changed or on a site or on way it read your site when some of him guide lines change.
Each error always can be fixed, the difficult is understand why is generated and how to fix it. You can teach me this.
What you say about "one error doesn't matter", can be good for a new site, or better nothing for that, but not for a big and good site as your one and my one. Also because an error in a file, for example a thread, a resource, or everything else, is moltiplicated for each content you have in that section, so an error of code that is there in a file of a thread for example, will be found in a big number of threads because they use the same files, so one issue can affect thousent of contents, that are also shown in the Search Console as errors and these let you loose the good position in the ranking you can have for that content. In your case have less impact because the argumets on Xenforo are only on your site and not in others, but if my site is about shoes for example I will have hundred of competitors and quality make the difference. The quality of every little thing is there on the site, I mean.
It must be a way to fix it, (as always). I will try to search it.
I know also the problem that is making Google focussing on the rich snippets about who try to manipulate these datas, so also for this is better to investigate to don't risk to be seen as this kind of behaviour.
For the rest how the others search engines valute our sites have few or nothng value, because the 95% of the traffic is generated from Google, so that is the first thing to have in order.
In each way I will keep you update if I found something about it.