The quest index 83 is achieved when the player talks with Indoril Ilvi (TR_m3_Draler Ilvi)  through the topic "Margia Sycora" after the Quest has passed or is in the Index 81.

THE BUG: The topic "Margia Sycora" isn`t introduced from anywhere or anyone. Indoril Ilvi can`t talk with the player about this topic,

SOLUTION: I suggest to use the NPC Rathys Madalvel (TR_m3_Rathys Madalvel), the one that hint you about Indoril Ilvi. Just use addtopic in his Result Box.