Hi, I think I'll split my answer into two parts. In the first part I'll answer your question as it was asked. In the second part I'll explain what I think about your question. The second part is just my opinion.
FIRST PART:
"It represents stealth and sneakiness and is used in operations where one wishes to proceed undetected"
"It is used to conceal and can render a victim unaware of impending personal disaster to where any actions attempted will be too late in coming"
The ISA Rune could also be used so that the person does not turn to a diviner to find out this information about you.
SECOND PART:
if the person I cast a spell on goes to a psychic or tarot reader,
Note: this is for my country, Italy. I don't know how fortune telling works in your country, but if you talk to me about online biographies of "psychics" I don't think there's much difference:
I think it is highly useless to worry about this. From personal experience, and after having also heard the confessions of online fortune tellers, etc. I assure you that they will always tell you only what is convenient for them, which often coincides with something you want to hear, or with something they are not responsible for.
In the past I relied on many online fortune tellers to divine about a girl from high school towards whom I was the victim of a toxic love in which she was only destroying me. The fortune teller literally invented all kinds of things to keep me on the phone, that I would finally solve all my problems within the following week, that she would make me happy and everything else that could exonerate her from any assumption of responsibility.
Once I asked about a rival of mine in love. The fortune teller even told me: "don't worry about him. He cheated on her and she found out". Something that had never happened, completely invented and that said in a different context would have gotten a romantic relationship into trouble.
And these people wrote in their bios: "psychic, witch, psychic/witch", etc. These things are quite uncontrollable and even if you don't cast a spell on this person and if you never intended to do so, the fortune teller could still make up that this happened.
I am talking about fortune tellers because they also used tarot cards and sibyls, etc. Cartomancy is something truly noble and sacred and these people ruin such a divine practice.
I think that the only fortune tellers that you can trust outside of yourself will be if in the future there are official tarot readers on JoS who are recognized by the High Priests and who, after checks, put themselves at the proper service of the community.
From what I have seen, the "sensitive tarot readers" outside of JoS are largely unreliable. And with this I am not saying that there are only scammers in this area. I myself have met an example of an honest fortune teller once. In fact I abandoned her because she did not tell me what I wanted to hear, that is, that the girl from high school really loved me.
However, the thing is so "random" from a statistical point of view that the person can turn to a scammer or an honest one with similar probabilities, to the point that the thing is uncontrollable and I would not worry about sincerely thinking of it as a problem, as you are doing. I wouldn't even waste energy or anxiety on this eventuality.