For the Isha prayer, some people may regard it as makruh and some may not regard it as permissible at all. (read https://www.google.com/amp/s/islamqa.info/amp/en/answers/10125)
I have not seen anything about the ending of tahajjud prayer being in the last 1/7 of the night. Some websites have said that tahajjud ends when fajr begins.
Some scholars have said that the time for witr ends when dawn starts so I do not know how your witr would be makruh.
“Pray Witr before morning comes.” Narrated by Muslim, 754.
Muslim narrated from Ibn ‘Umar (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) said: “Hasten to pray witr before dawn.”
Muslim narrated (752) that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Witr is one rak’ah at the end of the night.”
Al-Tirmidhi narrated (469) from Ibn ‘Umar (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) said: “When dawn comes, all the night prayers and Witr are over, so pray Witr before dawn comes.” Classed as saheeh by al-Albaani in Saheeh al-Tirmidhi. Also:
Al-Bukhaari (472) and Muslim (749) narrated that the Prophet (peace and blessings of Allaah be upon him) said: “The night prayers are two (rak’ahs) by two, then when you think that morning (dawn) is about to begin, pray one (rak’ah) and it will make what you have prayed Witr (odd-numbered).”