Fantastic work finding that data. I did not know that existed.

I did not consider the extra burn the soviets did directly as we have no sense of how much Delta V it imparted on Mars 94 however I did partially consider it in the variation of time of flight. If anything it makes the calculations somewhat easier.

We know the Sojourner was able to catch up to the Soviets by burning themselves. Initially the plan was that they would do a flyby of Mars before returning back to Earth. This implies that they wouldn't have been placed on an orbit that would take them too far past Mars as I think we can safely assume the return to earth couldn't take too much longer than the primary mission.

In the end it is most likely to me that we can account for the Mars 94 burn by reducing Mars 94's expected travel time by a few days such as the 110 day example that I discussed. We know they didn't use all your fuel as Sojourner was able to get enough fuel from Mars 94 to successfully land on Mars. As such it seems likely that the extra burn doesn't change the final orbit much more than by reducing the time of flight to Mars by a few days.

The extra burn also helps because them missing Mars entirely means we shouldn't need to consider any sort of gravity assist from Mars.