How equanimous we need to be to be in equanimity...? To me, what I consider to be re-observation and equanimity seems like the long progression of one stage most of time. It starts with tension everywhere and as I gather my mind the tension is less difuse, move away from the limbs, into the back, into the spine, then into the neck. Still, there was time when the shift was more radical from the foetal position to clear panoramic equanimity in a matter of seconds.
To feel equanimous doesn't necessarily indicate that you're in 11th ñana, equanimity towards anything which arises is required for insight practice in general. 11th ñana is called "Knowledge of Equanimity Regarding Formations", the presence of equanimity as a feeling is simply a side-effect and not an indicator in itself. Re-Observation moving in to Low Equanimity isn't like one long progression, there's a sort of 'stepping up' thing that happen in late-10th/early-11th, which you can notice if well concentrated; for me, there's always a point of transition between the two stages which is either noticed immediately or just after the fact.
The section I've emboldened suggests to me that you're actually still in 3rd ñana, possibly getting into the early stages of 4th when you go on to mention "clear panoramic equanimity"; there are some definite similarities between 4th and 11th which may also be causing you to get mixed up with this, there's a panoramic quality to attention
but if you become complacent and practice as though you were in Equanimity, focusing on concentration over insight, you probably won't 'get it' and cross the A&P properly. There are some major similarities between 3rd and 10th ñanas, but what I'd say is that Re-Observation is more about the mental aspects, whereas it's much more physical in 3rd. The big distinguishing factor between the two, for me anyway, is that 10th is much more harsh and quick in terms of vibrations which can make it seem like your mind is being hit with electricity or something.
I guess, if following re-observation one find himself feeling equanimous, then he is free to call it equanimity. It still not necessarily high-equanimity, which I'm not sure I ever experienced. From my understanding, the experience of the panoramic stable vision belong to equanimity (?).
A fair point, as long as you know that the feeling of equanimity, which can be cultivated at any time with a bit of practice, does not necessarily indicate that you're in "Knowledge of Equanimity Regarding Formations" then it's fine. Getting into Equanimity is something quite distinctive but feels so completely normal that you could easily become complacent. When you do get into Equanimity there are a few things to keep in mind as there's a slight change in the way you practice that's required if you've been focusing on insight: Balance concentration with insight as 11th ñana is 4th jhana territory, don't go looking for sensations as they'll present themselves in this clear, effortless way so that you can simply observe, and experience, their impermanent, empty and inherently unsatisfactory nature. This isn't to say that you shouldn't continue to investigate, it's just that it's a gentler, more organic approach which can allow you to look closer at what seems to be observing, the sense of a "subject" to these luminous "objects". See how even this is no more than a pattern of sensation which is subject to the 3C's, just like anything else you can possibly observe or which seems to be observing.
When I get to really relax my neck to the pain that there is just a slight vibration left at the base of the head, I get some sporadic very short luminous events that trigger spams in my legs.
This sounds like it could be early 4th ñana, what do you mean by "short luminous events" as I may be using the term in a different way to you?
Do you notice these spasms occurring anywhere else in the body? Do they seem to originate from anywhere? Where do they start and end? Investigate these sensations too, it sounds like "kriyas", which in this context refer to energetic movements through the body and are common to most insight practitioners.
As far as your practice overall goes, I wouldn't say you were deluded or anything!
Understanding the specifics of this model and how they line up with your own practice can be a nightmare, it took me
a lot of strong, consistent practice and study of the techniques to really understand (but not before making a total arse of it on more than a few occasions) it in a practical, useful way. You can learn about models intellectually, which is fine, but to understand what their symbols and language refer to experientially is a different, and much, much more interesting way to go about it. I'll try to get a chance to check out your practice thread and see if there's anything useful I can suggest.