There is a long layover and she should be fine. Please consider preparing a card with flight and terminal details she can show it to others and ask for directions just in case the wheelchair assistance is not sufficient.

You can also add images to her phone with each image containing both Nepali and English text about common requests she may need to make at the airport.

Wheelchair assistants did the same to my mom exactly in Chicago although she managed to get her flight to DC. Blame the tip culture in the US. I think the wheelchair assistant thought that my mom would not tip. Assistants in the rest of the countries do their jobs without tips. I definitely trust Koreans.