By self-honest, I mean being able to accurately assess your own strengths and your shortcomings. Also being in touch with what you truly prefer and value, not what you should prefer. Is there a tendency for some types to be more self-honest than others going by this definition? Or is more an indication of psychological health and not really type related.
I think it's mostly a measure of one's psychological health and ability to introspect. I think that INxx types might have a slight advantage here because of the I and N in combination allows for introspection and to see patterns in one's behavior. The part about being in touch with what you truly prefer suggests healthy Fi use. Fi dominants may have a slight advantage in that regard, with emphasis on the slight.
Like I said, I think there may be a very slight correlation between self-honesty and type. Mostly it's about psychological health. There are ESTJs who are very in touch with themselves and INFPs who aren't so in touch.