In Step 7, "shortcomings" is the "character defects" from Step 4.
Which column, or list in the 4th Step did we make a list of "shortcomings" IF they are different? We weren't instructed to make one.
Bill W. was attempting to write more eloquently -- by not repeating the same words redundantly. I'll see if I can find the supporting reference for this, for you.
I have heard AA speakers who've added some spin to it that would indicate to them, that shortcomings are a "lack of" something -- for them. It makes for an interesting talk -- but it's twisting the meaning to mean something that it doesn't mean.
The idea that "shortcomings" to be a "lack of" something -- would best fit into Step 10. Not Step 7.
Steps 1-9 is the "personal housecleaning." We're cleaning house. We're bagging up the garbage and taking it out to the corner and asking the trashman to take it away. "Removing" the defects of character.
In Step 10 -- now, with a clean house -- we begin to "re-create" something different in the house. So, we make a list -- and it can be a list of things that "we lack". Something good that we want to acquire to fill the void of what was removed during housecleaning.
What's the purpose of Step 10?
a. To keep the house clean.
b. To "grow in understanding and effectiveness."
How might I become more effective? I might start by "not being tardy to my appointments -- or on my job" (a lack of commitment and discipline).
Ahhh? Discipline!

And, Bill mentions Discipline on pg 88.
"We alcoholics are undisciplined. So we let God discipline
us in the simple way we have just outlined.
But this is not all. There is action and more action."