Absolutely.
btw - if they are heading to F and you don't mind giving them one of the keys ahead of time then I'd suggest having one be found on the body of a dead demon (there is a description of one in the empty rooms description fillers at the beginning of the book that has the demon's body regenerating at the same rate as it is being consumed by insects - or something like that). Had my players spend quite a bit of time making sure that the regeneration ended up being less effective than the bugs in order to finally kill it off, but they found one of the keys from F (thus how the demon was able to escape).
Also - you might want to run a trail of crumbs for Jolinaar's movements from I/M through to H in order to foreshadow meeting him, or if you have a druid / cleric of nature in the party then tie in the dream sequence with Belatu-Cadros (the celestial treant). Have the party members who are also garrison members carry either messages or perhaps some form of communication device to the garrison in G so that the two celestial garrisons can reestablish contact.
I'm also planning on having a low rumble from the lava river be audible/felt once the party is getting close to the edge of I, and would have also done so if they had headed through F. Any dwarves in the party should "feel" the stresses beneath their feet (harder to do in I because of Madness and Anguish and the flesh covering the walls) being caused by the lava flow and split where the earthquake had divided the dungeon.
I've told the garrison members in my group that there is a hidden self-destruct within the Tomb (region N), but that the garrison members in E did not know either what it was, nor how it worked. Perhaps if you want the party to go to N after H then some hints could be dropped by the garrison in E and elaborated upon by those in G.
Maybe they could find a elf in F who was trying to reach E from G but had gotten lost in the maze.
While there are good plots within each region I really feel that the whole scope of the place is dimished without having some overarching story threads to tie the whole thing together.
Good luck with region F.