As a framework within which to discuss spiritual maturity, I think it's important to recognize that there are things that can be said privately that can't be said publicly - in ALL groups of any kind. That's just social communion and sensitivity. On the other hand, I say things all the time in church that others would have a hard time saying without push-back, because I've had to do so all my life and have become fairly good at doing it in a productive, acceptable way - and because everyone knows I'm a "faithful", orthoprax member and not a threat in any way.
Spiritual maturity, to me, is about being comfortable with reality (mine and others'), even when there are parts of reality (mine and others') that I am trying to change. It's not expecting more than people can do and be (including myself). It's an empathetic orientation - even when there are things that bother me and that I am trying to change. It's judging carefully and minimally (only as much as is absolutely necessary) and always remaining open to the possibility that I might be wrong in even those judgments.
Spiritual maturity, to me, is close to "perfect faith (whole, complete, fully developed hope)" - or, recognizing the limits of my (and others') understanding and being at peace with those limits. That "limitation peace" is the foundation of growth, since it allows me to pursue "further light and knowledge" while being okay with my (and others') dark sight in the moment.
Spiritual maturity, to me, is knowing what you know, believing what you believe, understanding that you don't know what you don't know, etc. - and realizing that every one of those lists is subject to change - and being at peace with that possibility.
Spiritual maturity, to me, is being totally fine that not everyone is spiritually mature - and that some people are really, really spiritually immature.