その方法までは解読できません the role of まで and the meaning of the entire line

Question

I have the following situation in some fiction I'm reading. Person B comes to a world looking to do something. Person A arrives afterward looking for B. As soon as A arrives she starts monologuing about probable B's intentions. Something along the lines "She'll first go for 'group of people' and after contacting them she'll go for 'Plot relevant thing' that somehow ended up here and try to acquire and bring it back home."

After recounting what she thinks B's plan/objective (目的) is she says the following line:

その方法までは解読できませんでしたが

こんな遠い世界の情報収集なんて

B独りでは無理でしょうし…

As of now it seems she is saying:

Up until that method/plan it's undecipherable (the rest of the data) but it seems plain that it B couldn't have gathered this much info on so far away a world alone...

The thing that bothers me is that その方法までは because I'm not sure what that is supposed to convey. I'm assuming that その方法 is the plan she just described. And so she is basically saying that everything before that plan in the database is unreadable. But it kinda feels strange to say UP UNTIL in this kind of context.

So, am I right oooooorrr.....

Answer 1

その方法 should be simply "the method for (achieving) that". So there is a contrast between "the plan (itself)" and "the method to complete the plan". In other words, she's saying she could decipher what B wanted to do, but not how B could achieve it. (I'm assuming the context you provided is reliable. If you want ask about what その refers to, please do not omit the previous sentences in Japanese...)

This まで is "to the point", "as far as", "to an extent". In positive sentences it can be simply translated as "even". See this.