Verses 14 and 15 interrupt Paul's main argument to give the reader extra information. If you have a way to mark an interruption like this in your language, you can use it here.
# Gentiles, who do not have the law ... are a law to themselves
The phrase "law to themselves" is an idiom that means that these people naturally obey God's laws. AT: "have God's laws already inside them" (See: [[rc://en/ta/man/translate/figs-idiom]])
# they do not have the law
Here "the law" refers to the law of Moses." AT: "they do not actually have the laws that God gave to Moses" (See: [[rc://en/ta/man/translate/figs-explicit]])