Unfortunately, Ruh. I cannot accept a character that has magic invulnerability. Though, I have accepted Fran with the use of her Anti-Magic vision, if it was a mistake or not. That is still up in the air. But I've concluded that overall anything that can nullify magic is too op. Because most of the Antagonists, but not all, use magic as their so-called shtick.
We will need to have a compromise here, I'm willing to allow her to have the ability to resist a few magical attacks. But her "powers" can't withstand extremely powerful magical attacks from Lord Bloodfang and Lee. While she has a certain resistance to it, she is not invulnerable or immune to magic. If you accept this, we will move on and we'll see how it proceeds throughout the RP, should it become a problem, then we will need to find another compromise.
Also, I'm getting a vibe of Stahl Mädchen that she isn't a team player. I won't accept that, because like stated in the rules.
Whilst, Lone Wolf characters are accepted, with the only exception that their plot throughout the RP changes them into becoming team players. If I accept this and throughout the RP I don't see significant change, such as character development that this character, is more than just a mercenary and is a team player. There will be problems. So to you and anyone who has "Lone Wolf" characters in a Group RP. Don't back on your word, I see all, I know all. And if you don't hold up to your agreement, I won't either.
Also about Fran, if you lost the will to play this character, then you will need to let me know what is going to happen with her. Also, I don't want you to end up filling your character slots, with characters that you don't want to play, so I advise rational and good thinking with a bit of inspiration slapped onto it, to make characters that will last. As of now, you have two characters and one still waiting to be accepted.
A friendly advise, as a fellow Friend and GM. I suggest making Stahl Mädchen more unique with a personality that only can be hers, so far I don't see mildly differences between her and Fran.
So, do the changes I've asked you with the abilities and then let me know what kind of character archetype she would be.