en_tn/rom/11/12.md

if their failure is the riches of the world, and if their loss is the riches of the Gentiles

Both of these phrases mean basically the same thing. If you need to, you can combine them in your translation. Alternate translation: "when the Jews failed spiritually, the result was that God abundantly blessed the non-Jews" (See: rc://en/ta/man/translate/figs-doublet)

the riches of the world

Because the Jews rejected Christ, God richly blessed the Gentiles by giving them the opportunity to receive Christ.

the world

Here the "world" is a metonym that refers to the people who live in the world, especially the Gentiles.