It would be hard, coming from outside the RCC to understand how the Church sees this passage. The Church being universal and spanning the globe and all cultures empties itself from the subjective interpretations of specific cultures and the emphasis those cultures put on passages. Emphasis, not necessarily intended by the inspired author. This is especially noticeable in American Culture (outside and inside the Church), who seemingly but unknowingly, includes in their subjective interpretations those values that are important to them. So, what am I suggesting here. Primarily, as assumed in the question, that there is no “simplicity” of Romans 10:9-13.
The scriptures to Roman Catholics are not broken down into individual versus; they are looked at as a whole, with all of the Word taken into consideration. So when it comes to Romans 10:9-13, a Catholic can say with full confidence that what is being stated is true within the context of the complete Word.
“There is no difference between Jew and Gentile” When the Lord Ascended into heaven leaving the Apostles to grow the kingdom, the remnants of the old Guard, the Jewish leaders through the Greco Roman world, were slowly brought into and evangelized into the Faith. There was resistance, issues of genealogy and OT priesthood, food laws, 613 works of the Law that had to be addressed which was not addressed by Christ but left to his Church. There was much Confusion. Pharisaic Christians, Pagan Christians of many cultures were asked to come together to a banquet where previously no contact was allowed. Customs and traditions, Valid ones especially like circumcision had to be addressed as you can imagine if you were older and had not been cut, the prospects of becoming a Christian with such requirements might seem gloomy.
Much of Paul’s writing echoes the Old Testament, Duet 30:14 for example comes to mind here.
As a Catholic, I simply have faith in God’s Word. Guarded and Protected by the ministry instituted by Christ from inception, not influenced by my subjective understanding or the culture in which I live, but by the Church that spans the globe who has preserved and defined to the modern world those teachings based on Faith and Reason.