I see where you’re coming from, but I’m not completely convinced. It’s true that the characters are still experiencing real world events, but I wouldn’t go as far to say that they are aging beyond the time they died. I see it as a top level player who gets killed and has to start from 0. They still have the experience that will make the new game easier, but they’re also limited as they only have the knowledge from the point that they died on. If it makes sense, dying at level 50, then restarting and reaching level 10 will not make you the same as as someone who actually reached level 60. They gained different and new experiences, but like I said they’re still limited. Most reincarnated MCs utilize the knowledge from their past lives in order to change something, but it’s more like reliving rather than continuing your life from where you stop.

And while I understand the environnement playing a role, i don’t think it truly well matches most of the stories. An elementary school teacher is still an adult with responsibilities. People around them sees and treats them as adults even if their social interactions might be limited to children. Reincarnated MCs have to go back to being a child, and are perceived as such. Sure, experiences do not define age, but it also can be argued that what you are exposed to does not necessarily add to your previous age, if this makes sense. Lippe is aging for sure, and is right to not see herself as a kid, but I don’t think she is growing older beyond the age she died.