Is what the Imam does — repeating "Subhan Allah walhamdulillah wa la ilaha illallah wallahu akbar wa Lillahi al-hamd" between the surahs, then re-reciting Al-Fatiha, Ayah Al-Kursi, the end of Al-Baqarah, Al-Ikhlas, and Al-Mu'awwidhatayn after ختم the Qur'an in Tarawih prayer — permissible?

Fatwas have clarified the ruling on saying takbir (Allahu Akbar), tahmid (Alhamdulillah), and tahlil (La ilaha illa Allah) after Surat Ad-Duha. Ibn al-Jazari mentioned that the people of Mecca say takbir at the end of every recitation (khatmah) starting from Surat Ad-Duha. Al-Ahwazi stated that takbir for the people of Mecca at the end of the Qur'an is a well-established Sunnah, and that some of them would adopt it for all surahs of the Qur'an. Ad-Dinawari mentioned that takbir is said at the beginning of every surah, not exclusively Ad-Duha or others, for all reciters.

As for tasbih (Subhan Allah), Ibn al-Jazari did not mention it, while he stated that tahmid is narrated from Ali ibn Abi Talib. Regarding tahlil, An-Nisaburi mentioned that what is recommended for the one saying takbir in prayer, according to the madhhab of Ibn Kathir, is tahlil, so as not to confuse it with the takbir of bowing (ruku').

As for connecting one khatmah immediately after finishing it with another by reciting Surat Al-Fatihah and the beginning of Surat Al-Baqarah, this is legislated (masnun).

However, repeating the recitation of the end of Al-Baqarah, Al-Ikhlas, and Al-Mu'awwidhatayn has not been mentioned by any scholars, which indicates that it is not legislated. And Allah knows best.