Throwing out some more ideas.
The SLDF staff structure (according to one little sidebar on pg.12 of FM: SLDF) was based on the German model (Ia, Ib, Ic, IIa, etc.) rather than the US model (CoS, S-1, S-2, S-3, etc) which I think is derived from the French model (but I could be wrong) and between the War of Davion Succession and the First Succession War the Federated Suns set up a militia system based on the Prussian Landwehr (I don't know much about the details of it) so German traditions seems to have been prevalent at the time (so the European capital of the Hegemony and probably of the Alliance previously may have had more influence. The US seems to have been hesitant about the Alliance to begin with and then many of the early colonies near Terra drew a lot of colonists from North America, so North American influence seems to have been a fading factor).
I read the description. It is close to WW2 (and Kaiserheer of WW1) era Heer staff system as it was at division level. The logic is that staff has following departments: I that handles fighting related issues (essentially S-2 and S-3) and II that handles the rear related issues (S-1 and S-4). There should also be III that is military legal/court system. Outside these division had bunch of specialist officers (like Air Defense, Engineers, Technical Issues, Transportation etc). Unfortunately none of those has been described (but probably should be). This is very commander driven system.
However, the most alarming issue in description is that SLDF had no permanent staff structure below regimental level and that they use dual-hatting to deal with that problem! This means that any and all SLDF units below regiment really cannot fight independently from higher level units and that they must rely extensively on drills and SOPs. This is something Wehrmacht never was.
Summa summarum, I detest idea of Wehrmacht being used as a model because there is no army in modern times using Wehrmacht as its model. Pretty much every NATO army uses US system now (and thus the Western Alliance would use US system as well). Thus coming up to it for pure fun seems to be a peculiar choice. Is there any good in-game reason they came up to it or was it just hack writing as usual (i.e. trying to project SLDF as some kind of proud soldier race)?
On second thought I started to ponder why to choose Wehrmacht as model for SLDF. I cannot see Star League promoting race war and militarism as reasons so I think that they wanted to make it all look ideal proud soldier race guys rather than harsh reality. This is by no means impossible, for example Roman army and its genocides are typically forgotten in promotion of its legions and martial image right now in popular fiction.
Next step is to look at things a bit further. Ultimately the function does follow form so it is also interesting to see where it takes us. Wehrmacht staff system is very commander driven and fairly similar to staff system used by British Army and Soviet Army quite recently.
Following staff systems are in use:
1) Specialist officers - this was used by almost all Bronze age militaries. You'd have a bunch of specialists who gave input when asked by commander.
Game effects:
Command roll: Leader with staff bonus
Staff work bonus: 1
Time delay: 1 for cycle
2) Fixed Staff - this was used by Rome and then Napoleon in Europe. Here the army recognizes need to have fixed positions where men were posted to aid commander. Officers are specialists in their own fields.
Game effects:
Command roll: Leader with staff bonus
Staff work bonus: 2
Time delay: 1 for cycle
3) General Staff - Thus is the Continental staff system universally used by all modern military systems. This originates from Prussian military. The idea is that there are fixed staff positions/sections that plan army functions and report commander whether commander wants help or not. Subsequently you have now special planing officers who specialize in planning (called General Staff Officers). The General Staff system can be organized in multiple ways but you have two general ways to look at it.
3.a) The US/NATO system assumes that all staff sections
are at least in theory equal and can give input to commander in staff conferences. The good part is that staff churns out fearsome amount of good planning but the bad part is that commander is often consumed by staff and driven by staff initiative (rather than other way around).
Game effects:
Command roll: Staff with leader bonus
Staff work bonus: 4
Time delay: 4 for cycle
3.b) The Prussian Staff system (used by Soviet Army, Wehrmacht) practically divides staff to fighting and supporting sections. This concentrates commanding to fighting battles but hurts supporting and administrative affairs. It also takes a very brave staff officer to say against commander which can lead to problems along the line.
Game effects:
Command roll: Leader with staff bonus
Staff work bonus: 3
Time delay: 2 for cycle
The final axis is the role of commander. Some armies (US Army) make commander rely heavily on staff advice while others (Wehrmacht, Soviet Army) rely on commander making the decision.
If we assume that SLDF was born on fighting short decisive wars and its original commanders and their fighting methods were very commander driven, the staff method could easily be based on dividing the staff circus into two parts: one for fighting and one for supporting. Then you codify this in manuals after the war.
The Wehrmacht part is probably more of trying to make a break from existing US/NATO structures and thus selecting army that supports the above-mentioned staff structure and looks suitably bad ass (while propaganda and history writing taper off any unsavory details of Wehrmacht crimes and failures). Since soldiers like looking bad ass they do that as long as they are told that they are emulating "pound for pound the best army in world history" etc...
