It’s important to understand the nature and purpose of the Catechism.
The Catechism is ultimately a compendium of Church teaching applied to our present historical context. The teachings contained therein receive their authority from the primary source they are based upon, not by virtue of simply being in the Catechism.
Thus, even within the Catechism, there are some teachings that are more authoritative. Not every paragraph contains equal weight.
The manner in which Pope Francis chose to edit the paragraph in the CCC on the death penalty doesn’t really have precedent. He didn’t issue any sort of apostolic exhortation or motu proprio. It came more in the form of a letter. In making the change, he did not invoke infallibility.
That said, I see no reason why Catholics shouldn’t support the pope in his application of teaching to the present day.
So far, this has been the only modification to the CCC (since all the modifications that were made back in 1997 with the release of the 2nd edition). I recall a news article a few months ago that said Pope Francis was considering adding some things about “ecological sins”. Thus far, nothing has come of that speculation.