Aw man. Yeah, that is very close all across the board. The oxygen level is like being a few kilometers above Everest. If you were already fully acclimated to low oxygen then maybe you could survive for a few minutes to hours -- hard to say exactly. Without acclimatization you would pass out in about 15 seconds. Same deal with the CO2 and SO2 -- you would be overcome on a timescale of minutes to hours.
That sounds pretty bad, but in the context of typical SE atmospheres that is a really nice find.
Actually I would pay my whole money to go in an exoplanet in which I can survive for some minutes without any kind of life assistance! I guess we can also survive on Mars for a few seconds, but breathing the air of an exoplanet is probably a very exciting experience
The SO2 in SE should be tweaked to only appear on planets with no oxygen creating photosynthetic life and a reducing atmosphere, as it can accumulate, but not in atmospheres with free O2. Same for CH4, with oxygen it can even be explosive. Contrary to what some folks on the old people said, high O2 content does not make an atmosphere explosive, oxygen is not flammable, it would just make life more active and fires more dangerous (consider that during the Carboniferous our atmosphere had 35 percent O2 and the land was covered with giant ferns with giant spiders and incests). What would be explosive is a mixed CH4/O2 atmosphere.
One thing I like about SE is that most garden-worlds full of life are not in fact immediately habitable to humans. This is likely to be true IRL as well - even a planet with a biosphere as rich or even richer than Earth is not likely to be shirt sleeves habitable, and Earth is probably just as deadly for them as their planet for us. That being said, a partial face mask would suffice in most cases like this. But personally, I think if humans ever colonise planets with a different native biosphere, they will be ideologically open enough for some slight genetic engineering to say, tolerate higher CO2 levels or some extremely toxic trace gas (consider that for example crabs cannot get poisoned by cyanide or CO because their blood contains a different oxygen carrier than hemoglobine).