Regarding facial expressions and body language i saw somewhere a suggestion that there could be options at character creation where you choose what type of person your character is and she/he would act accordingly during dialogue scenes, it would define if they smile a lot, they have a sad face in general or they constantly serious or just outright afraid of everything etc. as OP said they will never be able to cover all versions as thats impossible but they can try to give more layers to it (and maybe add a toggle if some people doesnt want to see these?). i imagine this would need a lot of tweaking to get it mostly right and it might be too much hassle to implement this at this point, but its an interesting idea
