Translating it this way, with the emphasis on "ki" instead of "ai", also makes more sense when we here or read of people saying "use aiki". It is a way of saying "use a particular kind of ki".
That begs the question -- what kind of ki? There are probably many ways of looking at it, but grammatically, they would all boil down to two different types, based on whether you take "ai" as passive or active:
Passive: "ki that has been harmonized" or "ki that has been unified"-- I would take this to refer to what people like Dan Harden, Mike Sigman and Rob John refer to in terms of unifying and resolving contradictory forces inside the body, which then produce a specific type of power that can be applied to techniques. Aiki here could also mean something like "Ki that is produced by meeting". I see many references in the doka that could be references to this idea, and the bits and pieces of information available about Daito-ryu seem to point to something along these lines. If anyone knows more to support or refute this idea, please feel free to chime in.
Active: "unifying ki" or "harmonizing ki" or "meeting ki" -- this could be a more commonly used translation of the term, though again it would be a type of ki that you would use. In this case, a type of ki that you use to match or fit in with your opponent. It could also probably be used the same was as the passive construction.
I'll leave the grammer and translation to you fellows. Speaking to the practical use I can see a delightful Japanese play on words.
"Ki that has been unified" becomes "unifying ki"
Passive: "ki that has been unified"-- is needed to affect a change in you. once in yo is relsoved in you the effects when another adds a foce to you is that the added force then gets resolved in you.
Active: "unifying ki" or "harmonizing ki" or "meeting ki"
Now the play in meaning.
Without one of the parties having resolved in/yo in himself (passive) the meeting with another will not produce a true harmony of ki within him from the added force. How could he?
Instead what will happen is just two forces meeting; the external push-when-pulled, turn-when-push, that most "call" aiki.
You are also correct in noting the references where Daito ryu can say "Apply aiki" Or "create Ki by meeting," How would one "create ki by meeting? The opponent is drawn to your unified ki and moves with you unwillingly. This is not as far fetched as it sounds as it can be expressed in more practical projection throws, draw-ins, leg sweep, or punches. Not just in aiki-no-jutsu. And all through applied Aiki age, aikisage or fure aiki.
Were the pull when pushed turn when pudsherd model correct (its not) then the Daito ryu model makes no sense.
So "Ki that has been unified" becomes "unifying ki"
without the former you have no hope of accomplishing the later. Rather you will just do external arts, maybe really, really well, but its still just external arts.
Excellent job Josh