We have required functionality base on collapse and Expand button on row level so tree functionality does not work for our case.
Collapse and Expand buttons can be used instead of default node renderers in treegrid with help of column.render
I have able to collapse and expand rows base on the row button.
I don't see it working in your jsfiddle. Please use inbuilt Tree() API to expand / collapse rows instead of writing the logic from scratch.