There's a different translator for On the Calculation of Volume III. The first translator retired. That's weird. I would think they'd wait til the whole thing was done. Who knows. Tara changed between book 1 and 2, though the translator stayed the same. Anyway, they changed translators volume to volume of Remembrance of Things Past. Voices change with time, even when they're stuck repeating the same day, ad infinitum.