Yes, there are 8 incidents and you only need to get the isolationist result from 6 of them.
Note that the achievement is worded poorly. Many people (myself included at one point) erroneously believe the achievement needs the max isolationism level of the country, i.e. the isolationism level that gives you -0.03 war exhaustion and -15% stab cost. In actuality, each incident can either result in more isolationism, more openness, or neutral, and you need to get the isolationist result from 6 incidents to get the achievement (even if it doesn't actually move your isolationism modifier at all, since you could be at max isolationism already)