If I was to try and put a definition on low-fi vs mid-fi vs hi-fi I'd probably start with something like the following:
low-fi: audio products focused on price point and features over sound quality. These types of products might top out as the mid range offerings at a place like Best Buy. Even people that don't care about audio own these.
mid-fi: audio products where sound quality is a more significant factor while still being widely available. These types of products might start as the top end products at places like Best Buy and extent into the more entry level products at hifi vendors like Music Direct. People that either care about audio or just have enough money to get upsold tend to own these.
hi-fi: audio products where sound quality is the most significant factor and availability is limited. Only people that are actively seeking quality audio tend to own these.
There's going to be a lot of grey areas of course and it's all relative.
In my mind, Klipsch Cornwall and Magnepan are clearly both HiFi speakers.
Klipsh that you find at Best Buy are LowFi or MidFi and sometimes people unfairly judge a brand based on its most entry level products.