Q: As regards a baptized Catholic who never received any further catechesis and therefore no other Sacraments:
Chapter 4 simply says they “make a profession of faith in which they were baptized, receive the sacrament of confirmation, and take part in the eucharist.” I know (I think) this chapter is only included in the English-speaking countries and is not in the Latin.
So when we get to chapter 5 and their reception, there is no mention of the baptized, uncatechized Catholic. So the question is, does this person say the additional phrase after the Creed that those coming into full communion recite? And another question: would the renewal of baptismal promises (as at a Confirmation Mass) be sufficient to take the place of the Creed in those situation where these people completed their initiation when the Bishop was present at the parish for Confirmation?
A: The English translation considerably reordered the material from the typical edition of the RCIA, and in the chapters you mention (IMHO), this has caused the problems that you are seeing.
In Latin, chapters 4 and 5 are totally unrelated. Chapter 4 refers to baptized, uncatechized Catholics, and chapter 5 is the reception of validly baptized Christians from other denominations. They are in completely different parts of the book in Latin, but in English it looks as though 4 is the onramp to 5. I’ve treated this in my book, When Other Christians Become Catholic.
A baptized, uncatechized Catholic who needs confirmation and first communion does NOT make the additional statement about believing what the Catholic church believes. Either the creed or the renewal of baptismal promises will suffice.