I don't know about other players, but twenty-something planetary administrators, brigadier generals, and naval captains somewhat break my sense of immersion. On the naval side, I can ... sort of ... remedy this by changing the initial rank (in the scheme I'm using) from lieutenant commander to lieutenant, but that's no help for that twenty-three year old ruler of Earth nor for the young scientists in charge of 60 labs (nor for the first initial crop of naval officers).
An easy "solution" (I grant that the current setup might actually appeal to some players) would be to make initial commander ages early 30s instead of early 20s. I can better stomach 30 year old lieutenant commanders (or even lieutenants if they're senior enough to command ships at the game's level of granularity) or head scientists ... colonels would still be a stretch, but beggars can't be choosers.
Less easy, but probably not difficult to code would be a dynamic means of establishing initial age at world/game generation, so that those (especially, perhaps exclusively military) commanders that get/would get auto-promoted in the initial commander crop are aged appropriately for their (maybe soon-to-be) rank. If colonel is to be the R1 rank for ground troops, perhaps their initial ages could be set separately---they should be (or I'd like them to be, at any rate) significantly older than the navy's lieutenant commanders.
A slightly related "problem" are the brigadier generals commanding Marine
companies, which might fit a Star Wars-esque imagining (Han Solo didn't look like he could fit an entire battalion, much less any larger formation into that stolen shuttle), but doesn't quite fit with what I'm imagining for a force structure in my game.
It's all really minor stuff, but should be fairly headache-free to address if my suggestions appeal.