I think your observations and proposals of displacements you posited are good ones and grounded in a type of 'intuitive geometry' in the sense that you observe angle relationships that could be changed and what would MIGHT (or might not) need to be done to change them relative to an improved aesthetic balance. However, your past revision surgery (due to facial trauma 2 months after your maxfax surgery) puts a significant uncertainty wrench in the gears as it would apply to a decision to undergo another maxfax surgery to bring your jaw/s more forward.
As to the excess inclination of the front teeth (upper and lower incisors), there are orthos who do that as part of getting 'the bite right'. On the other hand, there are maxfax surgeons who want to decrease the angle of inclination of the lower incisors which involves plucking out the FIRST pre-molars in order to make room for the lower incisors to be pushed back which creates and/or increases the overjet and allows more advancing of the mandible. Could involve similar (extraction of both upper FIRST pre-molars) to make space to decrease inclination of upper incisors.
What we have here is an observation that there is excess proclination of the upper and lower incisors and also no 1rst pre-molars plucked in the process of creating more of an overbite aimed at more lower jaw advancement. You speak of an extraction of a 'baby tooth'that never turned into a pre-molar and it's unclear if this 'baby tooth' is the FIRST pre-molar. Even if it was, since baby teeth are usually smaller than adult teeth, you don't know if extracting the adult premolar (which would tend to be LARGER) would allow for even retroclining in a revision surgery (because the space left by plucking an adult pre-molar on the opposite side would tend to be larger than the space left by plucking the baby premolar you had plucked.
Obviously, there was some PRECLUSION for the surgeon to decide AGAINST plucking 2 FIRST pre-molars of UNIFORM size toward the goal of of advancing the lower jaw further. So, you would FIRST have to find out what the preclusion was. So, something limited bringing the lower jaw more forward. It could have to do with un-even pre-molar space from side to side and also a very small lower jaw and combos of both. Could also have to do with having BI-MAX protrusion; a situation where there is excess inclination of the upper and lower incisors but the solution to it is a type of surgery US doctors don't do. It is something where not only are the 1rst pre-molars (of both jaws plucked) but also the tooth bearing BONE is removed and cuts are made to move segments backwards. So when the proclination is moved BACKWARDS, they can get more double jaw advancement without the LIPS sticking out too much. Because your lips stick out and also because you have excess proclination of both upper and lower incisors, you could have BIMAX protrusion. Something that Asian doctors address but US doctors don't do that type of surgery. Basically, with bimax protrusion, the lips would STICK OUT TOO MUCH with advancement of the jaw/s due to the excess proclination associated with bimax protrusion. But for the entire protrusion to be moved backwards, a type of surgery is associated with that which US doctors don't do. The Asian doctors do that sort of thing to move the lip area backwards, in which case they can get more of a single or lower jaw or both advancement without the lips sticking out too much.
There are limits to how much they can advance the lower jaw and you would need to find out more from your surgeon as what limitations were at play because pre-existing limitations would tend to limit what could be done in a revision surgery and especially so when there is also a 'wrench in the gears' from a trauma and more surgery having taken place in addition to the possible start point of bimax protrusion that US surgeons don't 'fix' the same way Asian surgeons do.
As to no SLIDING genio, the reason for that would be that the displacement is a combination of vertically UP and horizontally OUT; the vector displacements over an diagonal cut. So, ya, your already short lower mandible/chin area would look shorter after a sliding genio and it would make the lip to chin 'groove' into more of an overly acute angle. However, there is ANOTHER type of genio that could afford some improvement in the sense that it could 'mimic' the look of more advancement to the mandible. The vector displacements are vertically DOWN and horizontally outward. Sine that type of genio involve separating chin segments such that there is a GAP left behind, it also involves a BONE BUTTRESS to the gap; a GRAFT. I call it a 'down and out' genio. So, determine IF reason the surgeon did not suggest THAT type was due to some preclusion against it OR if it's not the type of genio he can do.
So, in closing, I think there was a preclusion in addressing the type of proclination you have to the incisors that the next guy might not be able to address either and then add the risks of a 3rd surgery. I think the conservative choice would be to look into what I call a 'down and out' genio which would help mimic more lower jaw advancement.
