Thanks for sharing this.The way I understand this is that people will adapt a cognitive preference and motivational preference that suits them depending on the environment in which they are situated. To separate the two would be to separate them only in how they deal with different dimensions of human behavior and thought, but I honestly think the interplay is far more complicated than this.
I think there is a correlation between cognitive preference and enneagram core type in that a certain cognitive preference will lend itself towards picking up specific enneagram core types over other core types. Consider for example someone who values Fe in the ego block. So assuming the person's childhood experiences lines up with the withdrawn triad, the person is far more likely to develop into a type 4 or 9 than 5. With that said, I only speak of tendencies here as I do not think it is impossible for an SEI or IEI to be a type 5, but the likelihood of a person who values such cognition seems to overall also seek or be drawn towards coping mechanisms that fits their way of cognitively understanding the world. Type 5 being a competency type situated within the head center and whose primary focus is that of intellectual analysis and understanding of the world would thus fit someone who favors logic in the ego block more than someone who favors ethics. With that said, again, only tendencies, I don't like to draw hard lines here.
I also think enneatype descriptions themselves kind of suffer from a feedback effect where they are pigeonholed or stereotyped around a certain cognitive output, so there is also the belief that a type 5 cannot be logical or a thinker. This also partly misses the point what enneagram is about though, since they are simply motivations of how we cope in the world.
I was thinking of how an ESI-Se type would be like internally as a 5 and what aspects of life they would focus on and try to understand, if so. With Fi leading, I can imagine that an ESI could be very concerned about finding or understanding morality, both in terms of who they are but also when it comes to others. To seek understanding in what is ethical and unethical and to have the power to universally apply these ethics.
In the end, I find that regardless of cognitive preferences and enneatype, one will see how both interplay in a way that simply makes sense within the individual regardless if one thinks that it is a (un)common combination or not, assuming they are properly typed. This is because they are in my opinion both the result of the same source, that is the person who express this kind of cognitive preference and enneatype motivations. As such, they will be very interwoven within the individual where it will simply make sense, as the enneagram will lend itself and support the favored cognitive perspective.
Do you think that cognitive preferences are formed independently of environment? Everything seems to suggest that enneatypes aren't, so I wonder if this is one of the major distinctions between the two systems.