When in Yoshiyah's reign was this?
Rashi: It is when [Hashem] commanded me to return the 10 tribes.
Radak #1: It is before Yoshiyah and Yisrael repented, for it discusses idolatry. Yoshiyah eradicated the idolatry after he repented. Even though it says "Lo Shavah Elai
What is "Meshuvah"?
Rashi: It is unruly.
Refer to 3:7:2:1-2 and the note there.
Radak: It is an adjective. It means rebellious, like "Shuvu Banim Shovavim" (verse 14).
To whom does "Yisrael" refer?
Rashi: It is the 10 tribes.
"Ha'Ra'isa
Rashi: They used to go, while they were on their land.
Radak #1: Yirmeyah did not see it. His prophecy began 83 1 years after Galus Yisrael, and he said that he is a Na'ar! Rather, "ha'Ra'isa" means 'you heard' or 'you know', like "va'Yar Yakov Ki Yesh Shever b'Mitzrayim" (Bereishis 42:2) and similar verses. They used to go.
Radak #2: The verse discusses deeds of remnants of the 10 tribes in Mitzrayim, and Menasheh, Shimon and Naftoli who were [still in Eretz Yisrael] in the days of Yoshiyah. It says "uv'Arei Menasheh v'Efrayim v'Shimon v'Ad Naftoli", "Asher Asfu
Texts that say '23' are mistaken. Yirmeyah's prophecy began in Yoshiyah's 13th year (1:2), and in between were the 15 years added to Chizkiyah, 55 of Menasheh and two of Amnon! Also, even one who is older than 23 could call himself a Na'ar! (Above, Radak said that perhaps he was old! Refer to 1:6:4:2.) Presumably, Radak wrote 'Pei Gimel' (83; some years of the reigns were incomplete), and the 'Pei' was mistakenly copied as a Chaf. (PF)
Why does it say "va'Tizni"?
'Rashi': The Yud is extra; they did idolatry (which is called Zenus).
Radak: The Yud is in place of a Hei; it is as if it says va'Tizneh. The same applies to "Tzur Yeladcha Teshi" (Devarim 32:18), "v'Chatasam Lefanecha Al Temchi" (18:23).