Has the addition "generous" in Sheikh Al-Albani's "Sahih Al-Tirmidhi" been missed, or is it correct according to him, and why did he not point out that it is an addition if it is not proven by him, knowing that he mentioned in Al-Silsilah Al-Sahihah that it is an addition from one of the scribes?

The addition of the word "Kareem" (Generous) in the supplication "Allaahumma innaka 'afuwwun tuhibbul 'afwa fa'fu 'anni" (O Allah, You are Forgiving, You love forgiveness, so forgive me) is not affirmed by Sheikh Al-Albani. He stated in "Silsilat al-Ahadith as-Sahiha" that it has no basis in the early sources and he suggests that it was interpolated by copyists or printers. He supported this by noting that it did not appear in the Indian edition of "Sunan at-Tirmidhi" and that An-Nasa'i narrated the hadith without this addition, from the same chain of transmission as At-Tirmidhi.