@pcj they know she’s extremely powerful, same as magiluka before Mary told her. It’s not really the same as invincible. While weird, it’s not completely out of norm for Mary to be extremely powerful as it’s been hinted her dad and reifus’s mom are also extremely powerful so Magiluka felt worried mary didn’t trust her. We already had a scene from back before reifus’s mom and the demon princess’s aunt know Mary is extremely powerful (though they confused her luck or isekai knowledge as intelligence)
Sacher doesn’t care to think about it, he just wants to get stronger himself.
Safina doesn’t care to think about it, she looks at Mary as her savior. It’s just natural to her Mary can do seemingly anything.
Prince has trusted her since she saved his life back in book 1, just want to help/support the country and her. He trusts her and not looking to grill her about her secrets.
And they still do kinda confuse her luck, isekai knowledge or some displays of pure strength as careful planning or cleverness.
Those from outside can’t really tell, peg her to levels like the ice blood witch or reifus’s mother. Since she’s always been altruistic, ice witch and reifus mom not too concerned either since their niece and son are Mary’s friends and just looking to see if they could recruit her once she’s old enough.