Let's read what Augusta writes about Si.

Introverted Sensation (Si)

Perception of the object’s internal situation
What? Si certainly perceives an inner situation, but of the subject.

We view an object’s internal state as a relation between events that condition each other. Through this element one perceives information about the way processes affect the internal state – one’s feelings and sense of wellbeing that this interdependence causes.

Interaction in space is nothing more than a reflection of one object in another. Objects reflect each other and evoke certain feelings in one another. An individual perceives direct outside information as feelings evoked by things happening around them. For example, a feeling of pain is nothing more than the brain’s reflection of a relation between one’s body and a process taking place in some part of the body and interfering with its functioning.

Ok. So this is partly cryptic and partly understandable. The outer world of objects evoke inner sensations in the person. Fine. But certain things here are incomprehensible to me.

When this aspect of perception is in the leading position, the individual is able to change the properties of the environment and the way people in this environment feel. They know how to avoid physical discomfort and how to protect others from it, which is determined by an ability to recreate once experienced aesthetic feelings.
Here she is talking about the environment, to change it to become more comfortable etc. But why would Si make this happen when Si doesn't deal with the outer environment at all (it's introverted). On the other hand, Se ignoring makes the person avoid too much stress and obstacles. So the result is a calming impact.

"Ability to recreate once experienced aesthetic feelings."
If there is any ability to recreate, then it doesn't come from Si alone, but from other functions that have been developed to the degree that they can recreate Si. But this is exceptional. Here I think Augusta is too idealistic, or she thinks that Si should have some outer use.

An excellent example of this is Peter Paul Rubens, who did not paint from life, but rather from his own memory of once experienced aesthetic feelings. When he was making a painting, he sought to give the viewer a specific aesthetic experience by recreating it. Such art is a revival of the object that provides the viewer with aesthetic feelings intended by the creator.
I don't know the type of Rubens but talking this much about an ability to recreate is missing the point of Si, because the function in itself doesn't have this ability.

Likewise, when an individual with this type of IM is cooking, they start by imagining how the dish will taste.
Really? Imagining is not exactly sensation. Si can be used when cooking but then it's more interested in the immediate inner sensations that the food evokes. Tasting the food.

Such people can distinguish once experienced aesthetic feelings from new ones, and know how to collect and remember them.
An interest in sensation can certainly make one remember the impression. No doubt. Although the "collecting" and "remembering" is not really related to the function itself.

This is probably why there are a lot of people with this type of perception among the so-called “psychic diagnosticians.”
I don't know what she means by this last word. Maybe someone can help?

An individual with this type of IM is able to set their sensory aesthetic needs in opposition to the same needs of others. They know how to fight for the fulfillment of said needs, and can shape and refine their own and other people’s aesthetic tastes and habits. They have an ability to impose their understanding of aesthetics and comfortable life on others.
I agree to some extent, but it is unclear from where this ability to "impose" comes from. Ok, it's the base function so it radiates some strength into the environment. On the other hand, the type is Se ignoring is not very good at "imposing" things.

I think Augusta is assuming too much that the function is supposed to manifest itself in the outer world, recreating etc. But Si only senses on "the inside", and that's it. Maybe this misunderstanding has to do with Augusta's own extroversion.