Hi @Kuroyume0161, first of all, welcome back in the plugincafe community, I'm glad to see you here!
Unfortunately, this is not possible to use directly a BaseList with a TreeView and as you already figured it out, you have to maintain this list yourself.
While it's very nice that a TreeView offer this abstraction level, and allows to make a list from any kind of data, it has the overhead to builds this TreeView layer.
Cheers,
Maxime.