OP doesn't want to make the game easier, but more forgiving (which doesn't mean it will be easier).

Take T6 and T7 for example.
If someone gets eaten by mistake, it is not an instant wipe. Its not an instant wipe at a certain amount of stacks either, it depends on your skill and gear.
If someone accidentally sends out voice in the wrong direction and gets a person or two, its not an instant wipe. If it's a healer(s), the tank just has to hold it out for 30 seconds. If it's a melee DPS, just move the boss away. If it's the offtank and adds are coming, the party just has to stop attacking for a while. If someone is stoned where they are and gets shriek, everyone needs to run to the hiding spot (This happened to our party once and we actually made it through in the end).

Making a mistake makes the fight harder instead of impossible, and this is balanced by the ease of making the mistake. It's also not always easy to be able to recover, and it gives a chance for good players to shine. I think this is what OP wants.