Is it possible to to "fail" this audit? Even when larger than the 4000 kilobytes median threshold of is this not relevant since it's an Audit.SCORING_MODES.INFORMATIVE?

The audit should fail in this scenario, it only becomes informative when the byte weight is below the passing threshold. However, reading the article it seems like this "informative on pass" system is causing some confusion so I'm open to changing it and going back to "green+hidden on pass".

Why not make it red when above the upper limit?

The audit will appear orange but never red because it is mostly an information dump. There aren't any specific improvements that we can recommend that will necessarily improve CWV.

What does "roughly equivalent to 'resources'" mean?

This is a comment for translators. It is meant to give extra context to the word "Payload".

In the case of this audit and several others, the pattern to make an audit informative when it's passing is unnecessary and causes more confusion than it's worth. I think there are still some audits that benefit from this pattern (e.g. LCP element audit) but we this is a case where it's not worth it. So I will go through all of our perf audits that use this pattern and try and reduce our usage of this pattern.