The section of Romans in question is chapters 9 through 11, where Paul discusses the prospects for fleshly Israel in the face of its not accepting Jesus as Messiah. This is apparent even if one begins reading the first verses of chapter 10: "Brethren, my heart's desire and prayer to God for Israel is, that they might be saved. For I bear them record that they have a zeal for God, but not according to knowledge. . . . For Christ is the end of the law for righteousness to everyone that believeth." (Verses 1-4) The Jews already believed in Jehovah, and there is no historical record that an issue was made out of them not using His personal name in everyday speech. So all the quotations from the Hebrew Scriptures and the emphasis upon accepting "the Lord" are intended to encourage faith in Jesus. It is the WT that has confused matters by inserting the name "Jehovah" in the text. By reading the standard translations, rather than the NWT, it is obvious who "the Lord" is.
Quotations are made from the Greek Septuagint Version of the "Old Testament," and most scholars will agree that this version, in the majority of its manuscript editions, used "Kyrios" - the Lord - instead of the tetragrammaton. Hence, the original Christian Scriptures used Kyrios in place of YHWH. It's not surprising that the WT manages, on any given issue, to find a few others who agree with its "scholarship," and can even find quotes from older scholars who used the name "Jehovah" when it was more popular. (If the WT applied their own reasoning regarding popular pronuncations, they would now be using "Yahweh" because this pronunciation has now virtually replaced "Jehovah" when used in the English language, except of course, when used by Jehovah's Witnesses and a few others.)
By their own admission, there are quotations in the Christian Scriptures that are applied to Jesus which, in the original Hebrew, referred to Jehovah. This is really a fact in favor of Trinitarian theology, regardless of the WT's attempts to explain it away. So the Lord we are told to call upon in order to be saved is Jesus.