From what I saw, part of the issue is that P-212 glass cloth isn't flammable, implying that there was a mistake in ordering or using P-213 instead.

As for how likely they are, spacecraft carry a pure oxygen supply and fires are one of the most dangerous things that can occur. Astronauts have died on the ground in training capsules that ignited, after which NASA paid close attention to any potential risk. As for the parachute, I don't know how likely they are to fail, but it effectively changes from a point of failure with one redundancy (can lose one chute, but still land) to a single point of failure that would result in the death of all astronauts aboard if it failed. NASA's pretty good about making sure that astronauts never die from something that could have been planned for.