Not sure why these reports always say things like "suggest" instead of "is".

Because this is science, not religion.

The thesis: Climate change is strengthening El Niño clearly uses the word "is".

Everything else is evidence, both for and against the thesis subject to interpretation.

Here it's "Something we can see in coral records correlates with what we'd expect given the thesis"

  The study doesn’t prove climate change is the culprit. But because the intensification coincides with rapid postindustrial warming and exceeds El Niño’s natural variability, the authors argue that human-driven warming is the leading explanation.

As the weight of evidence in favour of a thesis builds, so does the confidence in the thesis itself.

In this case, even the authors seems to agree that the finding is not "consensus-level" yet.

That being said, consensus would not necessarily settle the thing.

Even when the worldwide scientific community reaches a consensus and accepts using plain language (as in "It _is_ unequivocal that human influence has warmed the atmosphere, ocean and land" [1]), you still have a number of politicians begging to differ. [2]

[1] https://www.ipcc.ch/report/ar6/wg1/chapter/summary-for-polic....

[2] https://www.linkedin.com/posts/de-pire-en-pire-sur-france-5-... (Sorry, fr-fr)