as i said before, its quite possible to predetermine a lot of what you want in procedures, you can specify in the code that there must be a passable route between the alephs and buildings by all sorts of methods. i can think of one off the top of my head right now, simply blur the heightmap when generation is complete, as steep angles are represented by sudden colour changes, blurring would soften the slopes, make it impossible to have slopes of a greater angle than you want. If mountains are put in the game, it would be on purpose, making it impassible for ai, and a great challenge/shortcut for people.
that all said, i think your asking the wrong questions here, procedural generations could do everything we need, the question is if our programmer is willing or capable to deal with a very complicated programming problem. i may be wrong of course (i havent seen any of his work yet), but i think its unlikely that any new programmer to this area is capable of this sort of thing without getting a few years under their belt at least.
If its possible to find free code like the link i posted above then we dont even have to worry about that, since the tough algorithms are done and just fiddling with numbers should be enough.
dare, read the comments at the bottom of the link, the guy who wrote it said it wouldn't require much effort to make it multiplayer, you dont even have to make any complex changes, just change the random number to a number thats sent from the server, and its done.
the way it works is it gets a random number, and uses it to create a map, if the same number is input twice, the same map will come out, so if you have 32 computers connected to the same server, and the server tells all the computers the same number, they will all make the same map.
in case anyone is wondering how i know this, i just take an active interest in this sort of stuff since i found out about a procedural game that creates an entire galaxy with billions of stars, modelled to less than a meter all the way up to 100,000 lightyears (its multiplayer btw, just to prove that its possible) its not out yet though

called "Infinity: Quest for Earth"