We consider a null recurrent random walk $\mathbb{X}$ on a super-critical Galton Watson marked tree $\mathbb{T}$ in the (sub-)diffusive regime. We are interested in the asymptotic behaviour of the local time of its root at $n$, which is the total amount of time spent by the random walk $\mathbb{X}$ on the root of $\mathbb{T}$ up to the time $n$, and in its $n$-th return time to the root of $\mathbb{T}$. We show that properly renormalized, this local time and this $n$-th return time respectively converge in law to the maximum and to an hitting time of some stable Lévy process. This paper aims in particular to extent the results of Y. Hu [Hu17].