Wait what? They were moving from the Auspiya valley to Lozva. Then why would be their ski tracks in the Lozva's valley? Or is this a mistake or am I misinterpreting it?
This is Clark Wilkins summary, planned route in red, actual in green.
Igor tried to cut a corner, bypassing 663 and heading straight to 805. Wilkins suggests they were trying to navigate East of 805 (where the climb is steeper) towards 611, I think they were planning to rejoin their original route West of 805, on the East side of the pass. Either way they couldn't get up the slope of 805 so they headed South to 663 and made camp, too tired to dig the labaz or even a fire pit.
Now they were behind schedule. They sited the labaz 300m west of 663 in the morning, then Igor tried to cut another corner, setting a compass bearing of 320 degrees directly between 1079 and 805, which put them on the East slope of 1079, i.e. on the West (higher) slope of the pass instead of the East. They would have rejoined their original route on the downslope, Northeast of 1079.
They maintained a compass bearing because they were in a blizzard and couldn't see any landmarks. If they could spot 611 (where they ended up walking) they could have conceded altitude and rejoined their route, but they wouldn't want to do that, the climb had been a big effort. That's why the tent was on the slope, and why the search team were confused it was 500-600m "left" of where it should be.
Igor knew what he was doing but underestimated the climbs, they probably wanted to get to the Northeast side of 1079 but ran out of daylight. Wilkins points out they weren't recording certain details in the group diary because it was the official log which would be assessed for the grade III certification; and the personal diaries weren't being updated because they were exhausted.
Perhaps they found time to build a snowman before they set off from 663, and recorded it in the Evening Otorten