I had a stroke about 5 years ago. At first I couldn't talk or feed myself. I had 3 surgeries to clean my blood vessels and had 2 stints put it. Other than marine corps boot camp in the 70's it was the hardest thing I've ever done. But I had good insurance and went to rehab for several weeks. For me the milestone was when I could pick up peas with my fork and get them to my mouth. Then I learned to walk again and my speech slowly came back. I'm not near 100% now, maybe 70% but I'm still alive and working in my shop. I had to retire from my aerospace machining job. I hate that the most. I ran the shop and had a lot of good people. After I left and they brought a new foreman in within 2 months 7 people quit. The company almost didn't survive. I did a lot of coaching on the phone and zoom meetings.
I can't work a full day now and I take naps a lot, but I'm alive and kicking still. Give it time for your sister, the new nerve pathways take time to grow. They said our brain finds a new ways to get signals to our muscles, new nerves will grow but it takes time. It won't be 100%, but it's better than nothing.
I feel lucky, I was 62 when it happened to me. There was a kid in the next bed and he was 28 and all he could say was "yes" No matter when the asked him he said yes. After a month all he could still say was yes. He didn't have a good prognosis. I was walking by then and rebuilding my vocabulary. And keeping the peas on my fork. I feel so sorry for him, you could see it in his eyes. He cried a lot and I don't blame him.
Give it time for your sister, it's not over yet for her. Be there for her as much as your can. It meant the world to me when my wife came every night after work to see me.