en_tn_condensed/jer/50/20.md

In those days and at that time

These two phrases mean the same thing and emphasize that future time. See how you translated this in as Jeremiah 33:15. (See: rc://en/ta/man/jit/figs-doublet)

iniquity will be looked for in Israel, but none will be found. I will inquire about the sins of Judah, but none will be found

These two lines mean basically the same thing. Together they emphasize that Yahweh will completely forgive the sins of the people of Israel. (See: rc://en/ta/man/jit/figs-parallelism)

iniquity will be looked for in Israel, but none will be found

This can be stated in active form. Alternate translation: "Yahweh will look for iniquity in the people of Israel, but will not find any" (See: rc://en/ta/man/jit/figs-activepassive)

that I spare

They will escape the destruction of Babylon. This can be stated explicitly. Alternate translation: "that I allow to escape the destruction of Babylon" (See: rc://en/ta/man/jit/figs-explicit)