Are you sure...?
Is it the 'canon' translation, though?
It's semantically awkward to place Generals above Marshals without a terminological 'backstory' for which there is no apparent warrant in the Imperial Starfleet... but we have to explain "Grand General", and the impressive status enjoyed by "Grand General Brashin", and "General Carvin".
And what about "Superior General Delvardus" (who IIRC wore blackshirt uniform)? Daala's musings in Darksaber on of the warlords' "pompous yet meaningless titles" don't necessarily mean that "Superior General Delvardus" doesn't hold (or affect) a real rank, any less than "High Admiral Terradoc", whose rank is entirely legitimate. That almost looks like two General ranks that don't go below the Marshals... we could slot "Superior General" in the blackshirt rank-scheme above "High Admiral" and below "Grand General"...
It's a massive missile battery, and that can wreak absolute havoc with a fleet. One wonders just how much damage Pitta did to Grunger's fleet before Grunger kamikaze'd the Aggressor (200 ImpStars and an Ex, and the only way he can take out a torpedo sphere is to crash his flagship into it?!)... and we've seen what happened to the Lady Lucy with a single jury-rigged torpedo salvo at Thyferra...
The point is, though, that elsewhere (even if it is Cracken's Threat Dossier - it's somewhere in this thread) the Empire is given far less torpedo spheres than the ISB would suggest...
Moreover, inserting "High Admiral" at a higher point in the rank hierarchy would effectively demote every Fleet Admiral in the Navy with regard to Marshals in the Army and Starfighter Command.
It's not impossible. But I just don't like it. The only support you can give is "the ISB says it's like that".
Moreover, in rl, "Fleet Admiral" is a development of "Admiral of the Fleet", originally the singular rank of a naval c-in-c; the NR usage follows this pattern exactly. That's to say, a "Fleet Admiral" is more than simply an "Admiral". The idea that a "High Admiral" (essentially an uber-"Admiral") should outrank a "Fleet Admiral" (not just an 'uber-"Admiral"', but a slightly devalued Navy commander-in-chief) annoys me...
Back to WWI. There was a major British destroyer force at Harwich (I think), commanded by a Commodore (I know). Who would therefore have outranked a Captain commanding a battleship. However, the battleships were always attached to Rear Admirals and the like, so the Commodore wouldn't have been able to override orders, or send the battleship off on a jaunt. It's just the same in Star Wars. We might worry that the Sector has a Rear Admiral in charge of all Corvette level vessels. But if the commander of all cruiser size vessels is a Vice-Admiral, what difference does it make? If the V-Adm is incapacitated or otherwise removed from the chain of command, then the R Adm would assume greater importance. Even if his original Flagship is only a 2 gun, hyperdrive missing, flying chair!]
Nonetheless, while the ISB is probably the framework and the model to which all should aspire, it doesn't have to be true in every case. It stipulates 24 ISDs per Sector. Flashpoint: Brak Sector notes 30 ISDs in the Sector Fleet just after Yavin. (A WEG sourcebook and I bloody well lost it, too! I have only a few photocopies of some sections left!) Even if none of the Sectors we have in our mentioned sources have the requisite numbers, there are a thousand sectors, and we might only be looking at the aberrant ones.
Why can't they call in an ISD? They just talk to the next in the chain of command, explain the solution, and, if their superior agrees, they get an ISD or more. I don't understand. Sure you get things like General MacArthur in WWII, with the fighting on the mountain ranges in New Guinea. He refused to believe that the raw Australian recruits facing down elite Japanese troops were outnumbered and undersupplied, refusing their requests for reinforcements.
Borleias, if I recall correctly, 6 Torpedo Spheres are mentioned. 1.9km diameter ovals, so they are. But 6 isn't many for 1,000 sectors. So I'd have no probs accepting a much higher figure. Like Han's "Don't get jittery, Luke, there are a lot of command ships." comment. Saxton takes that as evidence that Ex is not an one-off, but Dr S also says that Han's referrng to Star Destroyers is slang. I question Dr S's methodology on occasion