Praise be to Allah.
We put this question to our shaykh, ‘Abd ar-Rahmaan al-Barraak (may Allah preserve him) and he said:
It is not permissible for them to offer Taraweeh before ‘Isha’ prayer or before the time for ‘Isha’ begins.
But because the time for ‘Isha’ is very late in their country, it is permissible for them to put Maghrib and ‘Isha’ prayers together at the time of the earlier prayer, then to pray Taraweeh after that. End quote.
And Allah knows best.