How to back trace the nested class data

Hi everyone： I have a tree structure(nested) data and with a weight value attached on each node( nodes_1 and nodes_2) . I want to find the nodes with the largest weight. How can I access these tree structure data? I attach a picture to show the data I obtain:

where nodes_1 and nodes_2 are trees structure. In one of the end of nodes, there is a largest value "cumline", how can I get it? Thanks you very much!