So I carefully watched the replay and there are 3 situations in which I had the lvl 25 track gold talent and it seemed to worked 1/3 times:

I got the +300 gold track talent, and the tooltip says track gold for allies is +420g

Afterwards, my ally kills tracked enemy for 331g (Goes from 900g to 1228g)

Then, my ally kills tracked enemy for 411g (Goes from 4216g to 5047g)

Then, my ally kills tracked enemy for 413g (Goes from 4616g to 5029g)

Match ID: 4046410984

Kill 1: Pudge dies in minute 50:53

Kill 2: Lina dies in minute 51:07

Kill 3: Spectre dies in minute 51:52