The math and route-plotting makes sense to me: people living with vascular dementia often have trouble with way-finding and spatial awareness. It’s not JUST caused by stroke, although that is usually the cause, so that’s why everything you’re seeing is about strokes. If she seems like she’s doing well enough, just keep an eye out for signs and symptoms like: short-term memory issues, increased spatial awareness issues, trouble initiating tasks or completing tasks, shuffling gait, etc. She’s in the early stage and knows that there are some issues, so this is really the perfect time to have an honest talk with her about both of your concerns. Make a plan with her. Talk realistically about what happens as it progresses. I don’t know how she was diagnosed, or why, and these are good things to follow up on with the physician.