OFB-8

So, will Bubuch play against Buchholz?
And if both players in the second match are absent at the scheduled time, will they both receive a technical loss (and Hellight will advance to seventh place), or will a coin be tossed?

Regarding whether Bubuch or Hellight will advance, it's still unclear. The last round could have significantly impacted Buchholz's position, so it's too early to count him out until all matches are played.
Regarding the second match, I think it's in their best interest to show up and play it out. Otherwise, they'll both receive a technical loss (there won't be a coin toss).