This is the first time that I have seen a catechism assert this. I have checked the Catechism of Trent, Douay, Baltimore and St Pius X....none mention this "symbolism". Having said that, none of them get into the Creation story in too much detail either.
In a couple of catechisms, however, they clearly state that God rested on the seventh day and, when discussing angels, they state that He created them on the "first day". Nowhere is there any mention or even suggestion that the day really wasn't a literal day.
It appears that the (same) JPII Catechism also discusses the Sabbath and that God rested on the seventh day (re: commandment to keep the Sabbath). So did He really do that on the seventh day or was that just symbolic? It doesn't say.
Bottom line for me: it doesn't surprise me to see what you posted. The JPII catechism is post Vatican II, a time where Modernists have been slowly and subtly changing teachings oftentimes appearing contradictory and causing confusion in the process.
That is the result of the work of doctrine by a committee of competing factions for the one true church, in contrast to those which have divisions.