Taweche/Taboche was first climbed illegally back in the 70s by a French team (Seigneur?) the got in some trouble for it. The Roskelley/Lowe route was on the East face, not north, and is the narrow shaded steepe face in the pic in your Brief Overview section. Pat Littlejohn and Mick Fowler climbed the NE buttress back in the 90s, Ueli Steck soloed the SE face in 2005 and an American team made a winter ascent in Feb 07 of a spur on the SE side. Probably more ascents, these are just the main ones. AAJ Online should sort the details.