Assalamu alaikum,

Please add the Islamic midnight time as that is the end time for Isha in the Hanbali school and also the start time of Davidic tahajjud pbuh per the hadith. Masha Allah you've already added the last third of the night for Islamic tahajjud, and midnight is even more important due to its ties to the end of Isha.

Jazakum Allahu khair.