She is still alive and has never wavered from her story right? I would hope she would have by now. Something still does not seem right about the Paines. She stated she was learning Russian to speak to Marina but she also was teaching Russian(if I heard that right). I am of the sense that she was some sort of handler but of course it's just an opinion.
From what I've read she learned Russian in college - both at Penn University and Middlebury college - and, as an adult, offered a course teaching it at a community college in Dallas/Ft. Worth (only one person signed up for it). She took in both Oswalds, in part, because they were desperately poor - Oswald lived on unemployment checks for long stretches - and she, based on her Christian/Quaker teachings, wanted to help them. She met the Oswalds at a party and talked to both in her passable Russian. It's true, as you pointed out, that one of the reasons she took Marina in was because she wanted to help her Russian.
My source for some of the above is Thomas Mallon's book, "Mrs. Paine's Garage." But some of this was also in her WC testimony and her grand jury testimony in the Garrison investigation (that's here:
https://www.history-matters.com/archive/jfk/garr/grandjury/Paine/html/Paine_0001a.htm).
There is no evidence that I consider remotely plausible that she was a handler for the Oswalds or that she worked for US intelligence. These connections between friends of her parents (while they were in college?) and the CIA or government aren't very persuasive. My late father worked for the FBI; I have never spent a second working for them. And really, do you know who your parent's friends were when they were in college? Before you were born? I sure don't.
Finally: if her and her husband's mission was to frame Oswald they could have made very serious charges against him. For example that he expressed hatred for JFK, or that she saw the rifle in the garage, or that he threatened JFK, et cetera. Neither Paine made any remarks at all implicating Oswald directly into the act. He was dead, they certainly could have.