This seems to say only focus on changing your mind and never try to change the world (not even with the mind). That's not what it means.
The Course says "The sole responsibility of the miracle worker is to accept the Atonement for himself."
This seems to say you should do your own self-study and keep it quiet and accept Atonement for yourself and not have anything more to do with the world or other people (waking up in isolation). That's not what it means.
The Course says "God's answer lies where the belief in sin must be in the mind, for only there can its effects be utterly undone and without cause."
This seems to say, the cause of all problems is in the mind therefore the answer is in the mind and you should therefore focus on undoing it in the mind and not attempt to do anything to the body. This is not what it's saying.
How about "all mistakes must be corrected at the level on which they occur. Only the mind is capable of error. The body can act wrongly only when it is responding to misthought."
This seems to say you must correct at the mind-level and apply the course at the mind-level only, where the error is. But it also tells us that the mind can mis-think and that its mis-thoughts seem to affect the body. This means that in those mis-thoughts, there is a level confusion, because believing that errors on one level can affect another level is level confusion.
Ok so how about this: "A major step in the Atonement plan is to undo error at ALL levels. Sickness or "not-right-mindedness" is the result of level confusion, because it always entails the belief that what is amiss on one level can adversely affect another. We have referred to miracles as the means of correcting level confusion, for all mistakes must be corrected at the level on which they occur. Only the mind is capable of error. The body can act wrongly only when it is responding to misthought. The body cannot create, and the belief that it can, a fundamental error, produces all physical symptoms. Physical illness represents a belief in magic"
This is a clearer definition of what's going on with level confusion. ALL sickness is a result of a confusion of the levels. When there is error on the level of the mind and the mind is mis-thinking, the body responds to this mis-thought because the body itself is a projection from the mind. The level of mind overrides the level of the body. The body therefore does not have power over the mind and the mind does not ever react to the body. The mind creates the body and projects it and maintains it and instructs it. The mind even tells the body what to experience and what to perceive and what to supposedly 'sense' with its senses. Yet the body does not really ever tell the mind anything it doesn't already know.
So when we have e.g. a belief that the body has a mind of its own, the body is affected by outside sources, the body has its own sickness, that the sickness is because of something happening at the body level, that we are a victim of the body, that the body's issues have power over us, or anything like that, we are in level confusion. It's a reversal of cause and effect.
"Physical illness represents a belief in magic". This means, when you believe that there are 'magical causes' beyond the mind's reach, outside of the mind and beyond the body, which have the power to make something happen, THAT is a belief in magic. When cause and effect are reversed, that's a belief in magic. And it's a level confusion. Magic = level confusion.
Correcting level confusion and thus sickness and thus 'doing the course' entails correcting error on the level it exists. Error exists on the mind level. We must recognize mind as cause and body/world as effect. You can't change an effect, which is why the earlier quote said not to change the world but change your mind about the world. If you change your mind, the body/world MUST change. Not 'maybe', or 'sometimes'. It must. The world comes from the mind. If miracles are not occurring, something has gone wrong.
You seek to change your mind about the world in order to correct mental error on a mental level. But that does not mean there are no 'effects' in the world or on the body level. The body level, a 'slave' to the mind, must reflect it. Therefore, there CAN be a reflection of 'heaven' on earth. A REFLECTION... not the actual thing. Elsewhere the Course talks about how this reflection is possible and how it is still one-step removed from the real thing. You can see a reflection of God in the world, but it is not God.
So no, miracles are not to do with shifts or changes in perception, or mental corrections as such. Miracles, moreso, as expressions of love, are what may happen when the shift/change/correction of mind perception has already been accomplished (through purification/forgiveness), ALLOWING love to flow through us and extend miracles to others. In this way, the world CAN be changed. The world CAN be healed. Sickness and death both can be abolished in yourself AND others because we invented them on the mind level.
So there is, to me, definitely an aspect here to bringing God 'to' the world, bringing heaven 'to' the world, bringing miracles of healing 'to the world'. BUT... not because the world IS heaven, but because it can reflect it temporarily. We are not meant to just focus on our navel and do mind correction in private and never have it have any effect on our body or on other people. The Course comes down to this:
Remove all of the blocks to the awareness of love's presence.
What happens when you remove these blocks? The awareness that love is present, returns to you. So now you are aware of love. And love is in you. And love is God. And God is powerful. And God loves everyone. So now that you're not standing in the way of God, and you're not creating error in the mind, what's going to happen now? Love is going to extend through you unhindered and uninterrupted by the ego and it's going to broadcast through you to the whole world. And that's going to produce healing miracles, and heartfelt interactions, and love and support for others. Unconditional love. That's very different from the Course being all about 'you' and your seemingly separate mind. Your mind is NOT separate from other people's. And your body is IN the mind. And the world is IN the mind. And all of this can be healed and corrected.