Yes, how things are affecting you is Si. You are basically saying the same things as I did but with other words. But It is also experienced in the environment, you are constantly leaving out this part of Si when you talk about it. Other than that our views are fairly close. You can of course say that this is also "how things are affecting you ".
The visual environment affects us and creates an inner sensation. But it is experienced as "outside". This is what Si-artists work with.
I know that you think so, you have said it many times. But he has an extremely good understanding of Si. Very introverted and analytical. Haven't you read what he says about the contrast Si vs Ni at the beginning of the Ni section of chapter X? It should be enough to see that he can tell them apart.Jung was not very good at describing Si either, he turned it into Ni.