So, from your reading, what's missing? (Or does an old thread already cover this?)
There's quite a bit missing and there are several old threads discussing it all. It's been a while, however, so a recap wouldn't be amiss.
Supply rules don't exist - You can pack up an army or two aboard your BatRons, jump from one edge of the map to the other, bombard/invade dozens of worlds, and never run out of Cheetos let alone boots, bullets, and band-aids.
Canonically the Zhodani seige of Efate was substantially handicapped by the continued presence of Imperial SDBs in the Louzy system. Those SDBs raided Zho supply shipping, and harassed Zho reinforcements. Without supply rules, none of that can happen in the game. Without supply rules, none of the commerce raiding repeatedly mentioned in canon can take place in the game.
Double Blind rules don't exist - Canonically, two operations determined to outcome of the war: A Zhodani sucker punch and an Imperial trap.
First, the Consulate launched the Abyss Campaign. That campaign was aimed at Rhylanor and the shock accompanying the loss of that world was meant to force the Imperium to negotiating table.
Next, the Imperium, in the person of Duke Norris, correctly predicted the Consulate's sucker punch and set a trap for it. Rhylanor was reinforced to defeat the Zhodani attack while other forces were stationed in the Abyss to attack Consulate assets when they withdrew from Rhylanor.
The failure of the Consulate's sucker punch and the loss of the substantial assets assigned to it meant that the Zhodani rather than the Imperium was forced to the negotiating table.
Because both players can see their opponent's forces on the map, neither of these operations can be attempted in the
FFW game without the use of double blind rules, yet the game has no double blind rules.
The Sword Worlds might as not exist - Only four Confederation worlds are shown and any Confederation offensive is greatly constrained by the odd shape of the map. The Confederation's starting location resembles the narrow end of a funnel. Making matters worse, half of Confederation squadrons can only reach Vilis, one of the so-called "fortress" systems, or Saurus, a system which can easily be made a "fortress" system.
Neither Vilis or Saurus have gas giants, you must control the mainworld to refuel in either system. Vilis has 1C SDBs and 15C troops against which the Confederation has no TL advantage. While Saurus has few intrinsic defenses, thanks to TL differential benefits placing the Imperium's
TL16 mercenary unit there will give the Confederation fits.
While half of Confederation forces can jump into the Imperium via Garda Vilis and Tavonni, the other half needs to fight their way out. And what of the canonical Confederation offensive against Lanth? The map funnels any Confederation thrust more towards Frenzie.
The 214th's Sixty Day Offensive cannot occur - Not only are most of the Sword Worlds "missing" but the Lunion and Glisten subsectors - and the Imperial forces stationed there - are missing too. That means the 60 Day Offensive can't happen in the game, the Sacnoth Fleet isn't destroyed off Sting, the 213th doesn't force the Gram Fleet back on Gram, the future Border Worlds aren't occupied, and the Confederation isn't knocked out of the war.
An entire portion of the 5th Frontier War cannot be modeled with the FFW game.
There are several other items too, but those should suffice to explain why I am hesitant to believe
GDW used the FFW game to plot the 5th Frontier War.