The Archangels would return, but found themselves unable to control the Rakurai array.
My speculation is based on the Charisian current re-armament, and throughout description of their new weaponry & ships. After all, if we have a gun in the plot, it should be fired at some point (A. Chekov), so I really doubt that all those descriptions of coll new Charisian battleships and airships are just to make book bigger

Problem is, that if Archangel's would return, all brand-new Charisian hardware would means nothing. Even if Archangels decided to play on Merlin's rules (i.e. just give technological ideas to their proxies), any relaxation of technological restrictions would make Charis current weaponry irrelevant. Basically, if you could use electricity, you could make anti-ship missile for blowing battleships.
So, the only scenario under which the current Charisian weapons & technology would have any practical use, is if both sides are locked on pre-electrical level. And the only reason why Archangels might do that, is if they aren't sure that Rakurai Array would not start to bombard THEM and their proxies, if they move too far.
After all, we already knew quite a bit of... strange things about Rakurai array:
* It did not react in any significant way on the discovery of Owl SNARC's nearby - SNARC's that obviously behaved quite suspiciously.
* In basically ignored Merlin's steam experiment.
* According to Wylsynn's family legend, the "mightiest weapon of God" could be activated only by putting the Stone (which probably contained Schueller's own personality recording) into the control panel inside the Temple. And those instructions are known ONLY to Wylsynn's. No one else in the whole Church hierarchy - including Clyntahn, who obviously knew... quite a bit more, than most of others - no one else have any clues about such things.
So, my speculations:
Before Archangel's departed, Schueller sabotaged the Temple control over the Rakurai array. He deactivated the return feedback from satellites, and changed access to the system, so only he - in therms of his own stored personality on the Stone - could activate the array. When Archangel's would return in future book(s), they would found themselves unable to actually control the Rakurai Array, and - fearing the possible reaction against THEM - would be forced to "play the game by the book", i.e. using their pre-electrical proxies.
