[Eric B]

So your arrangement agrees with mine on 8, 3, 7. Only I have them on the right edge instead of the bottom.

The 6 I matched with Supine as the upper left, which you're saying is 2. Those two types I see are similar, but since the 2 seems a bit more ambiverted, I give it the straight eyes like the left middle, which you're saying is 9.
The 6 is not thought of as "introverted", but its "fearful" behavior (in comparison to the 2) matches what in FIRO and APS is associated with low expressed behavior. Hence, the "shy/sad" eyes for the 6. But then you have that and the sad mouth for the 6 as well, in the upper right. Again, their nervousness we would associate with high wanted behavior, which would be a smiling mouth. Enneagram focuses more on negative traits, so I believe you do not see the more positive, "friendly" qualities of the type. But the negative qualities clearly match our fifth temperament Supine (and FIRO's "Inhibited Individual").

Meanwhile, the 9 I know is considered introverted, as well as agreeable. I guess it would have the general "amiable" image of the middle left, though the features don't match E/R. But the 9 is clearly Phlegmatic, which we considered ambiverted and inbetween people/task-oriented. I also see the 6 called an "ambivert", but the two types are "ambiverted in two different ways. The Supine expresses as an introvert and responds as an extrovert. That mixture can be considered a type of "ambiversion") (And I believe it is what give me my I/E ambiguities). The Phlegmatic expresses as an introvert or extrovert at times, and also responds as an introvert or extrovert. They can basically "take people or leave 'em". Others apparently see this, if they also thought the center face was 9.

The 5 I see as very critical (like the 1 and 8, as you acknowledge), so it should have the frowning mouth. And it is introverted, so it should have the sad eyes. The 1 and 4 are reversed. 1, 4 and 5 are very Melancholy. It seems the 1 has the Melancholy's perfectionism, the 4 has its "artisticness" and the 5 has its analyticalness. But the 5 seems the most introverted and directive together. The 1 is directive, but not as introverted, and the 4 is introverted, but not as directive.

Of course, you're using those other factors (instead of E/R), which I would have to analyze more.
One version of Enneagram theory that seems to support the E/R analysis to some extent, is The Enneagram: a Journey of Self Discovery (1984) by Maria Beesing, Bob Nogosek, and Pat O'Leary group the Enneagram styles according to Dependent Types (2,6,7), Aggressive Types (8,3,1), and Withdrawing Types (5,9,4). The Dependent types all have the high responsive score, just as we have them. The Aggressive types all towards the lower right corner [of the FIRO/APS matrix], with moderate to high expressive behavior, and moderate to low responsive behavior; representing "extraversion" and "directiveness". The Withdrawing types are low in expression in two cases, and much lean towards the lower left, conveying a sense of "introversion" and "directiveness". (Again, the Phlegmatic counterpart (9) is also considered "low E" as it is in many other instruments).