Interesting. I will try to look for anything corroborating that, because she was famously suspected to be a "Red" in the USA and she would've had her passport revoked.

And the only Western economist that officially was invited to Poland in 1948 was Oskar Lange.

Pugwash conferences started in 57.

To have access to any economic data she would have to be approved by the USSR in 1948 and then likely she would have to be on the exit visa list, on which she is not - in 1949 there are 3 Americans of which she is neither.

So if she were in Poland in 1948 or 1949 , with access to economic data, and left the USSR in 1949 she was better than Mata Hari. Good for her.