Wheelchair accessible

We are planning to visit Tateyama Kurobe in early May 2020 with our mom, who will be 89 next year. She can still walk but not for a long journey. So we normally bring wheelchair to assist her. She can climb up and down staircases, probably around 20 to 30 staircases, as long as the step is not more than 20cm height.
Is Tateyama Kurobe trip from starting from Tateyama station up to Ogizawa station wheelchair accessible? Especially at each transport exchange station, is there any lift or escalator? If not, then how many staircases that we must climb up or down in each station? Please advise.

According to their webpage they have wheelchairs at each station. That kind of sounds like it should be accessible:

https://www.alpen-route.com/en/wp-content/uploads/leaflet.pdf

In Japanese they explain a bit more:
https://www.alpen-route.com/information/required_help.html
Use google translate for the section that starts with a wheelchair symbol ( but also the one with the baby which is for elderly as well)

Enjoy your trip to Japan!