I know I already chimed in, but I'm still thinking this through.
The way I see it--and i'm not trying to add anything to the theory, here, i swear it (in fact, I'll say at the end where I think this is already covered in the theory)--any character can impact another character in many different ways. We'll call them positive and negative (for toward change and away from change, since that's how they were used above), for and against (as in the IC can push the MC to be for order or against chaos) and strong or weak (the ICs affect can cause the MC to say, 'eh, i'll consider it, maybe,' or can cause them to say, 'YES, I AM TOTALLY 100% on board with your LIFE CHANGING ADVICE!!!).
A steadfast IC that knows they know the solution would aim to have a strong positive impact on any character that doesn't solve the problem the same way. A steadfast IC that isn't confident in their solution may go from a strong positive impact to a weak positive impact, or even to a strong negative impact depending on how much they went back and forth on the issues themselves, as long as they ended on a positive impact. A steadfast IC might even think for a while about being a changed IC. But that IC journey is still having an impact on the MC whether strong, weak, negative, positive, for, or against.
When you ask if the sequences are all meant to show the IC pushing the MC toward change, or if they can show the IC losing influence, I think the answer is that an IC can push your MC toward or away from change, for or against a particular solution, and have a weak or strong impact while doing it.
Subjectively or objectively, I think your IC can be all over the place. It's really about where they end up (which character changed and which remained steadfast) and what affect did the IC have on the MC (did the IC convince the MC to be for or against something)? The strength or weakness of the ICs impact seems more like a barometer for how well the IC is doing as an IC. All of these different impacts can already be found in changed or steadfast (toward or away from change), start and stop (for and against), and the IC benchmark (strong or weak impact).
As an example, an MC might begin a story as enemies with an IC and move toward being good friends. In this case, the ICs impact to the MC might start out as a strong negative (the IC wants the MC to change, but because the MC doesn't like the IC, he doesn't want to change), move to a weak negative (MC decides the IC isn't that bad and can kinda see his reasoning) and finally to a strong positive (because the MC became friends with the IC, he can finally see that the IC was right all along change his path accordingly).