[guided]Fix $j \in \mathbb{N}$. We first need compact-uniform control of the holomorphic functions $F_{j,k}$ while the smooth weights decrease to the original possibly singular weight. Let $K \subset \Omega_j$ be compact. Since $\varphi_{j,1}$ is smooth on a neighbourhood of $\overline{\Omega_j}$, it is bounded above on $K$; define
\begin{align*}
M_{K,j} := \sup_{z \in K}\varphi_{j,1}(z) < \infty.
\end{align*}
The monotonicity $\varphi_{j,k} \downarrow \varphi$ gives $\varphi_{j,k} \le \varphi_{j,1}$ for every $k$, hence $\varphi_{j,k} \le M_{K,j}$ on $K$. This is the needed uniform upper bound in $k$. It implies $1 \le e^{M_{K,j}}e^{-\varphi_{j,k}}$ on $K$, so
\begin{align*}
\int_K |F_{j,k}|^2\,d\mathcal{L}^{2n} \le e^{M_{K,j}}\int_K |F_{j,k}|^2 e^{-\varphi_{j,k}}\,d\mathcal{L}^{2n} \le e^{M_{K,j}}\int_{\Omega_j} |F_{j,k}|^2 e^{-\varphi_{j,k}}\,d\mathcal{L}^{2n}.
\end{align*}
The last integral is bounded independently of $k$ by the estimate from the previous step. The [local $L^2$ mean-value estimate for holomorphic functions](/page/Local%20L2%20Mean%20Value%20Estimate) applies because each $F_{j,k}$ is holomorphic on $\Omega_j$ and gives sup-norm bounds on compact subsets strictly inside $\Omega_j$. Hence the family $(F_{j,k})_{k=1}^{\infty}$ is locally uniformly bounded.
By [Montel's theorem](/page/Montel%27s%20Theorem), a locally uniformly bounded family of holomorphic functions on a domain has a subsequence converging locally uniformly to a [holomorphic function](/page/Holomorphic%20Function). Passing to such a subsequence, write it as $(F_{j,k_\ell})_{\ell=1}^{\infty}$. We obtain a holomorphic map
\begin{align*}
F_j: \Omega_j &\to \mathbb{C}
\end{align*}
with $F_{j,k_\ell} \to F_j$ locally uniformly on $\Omega_j$. Since $H_j \subset \Omega_j$ and $F_{j,k_\ell}|_{H_j}=f|_{H_j}$ for every $\ell$, locally [uniform convergence](/page/Uniform%20Convergence) restricted to $H_j$ gives $F_j|_{H_j}=f|_{H_j}$.
It remains to preserve the weighted estimate. Pointwise on $\Omega_j$, the convergence $F_{j,k_\ell} \to F_j$ and the monotone convergence $e^{-\varphi_{j,k_\ell}} \uparrow e^{-\varphi}$ as $\ell\to\infty$ imply
\begin{align*}
|F_{j,k_\ell}|^2e^{-\varphi_{j,k_\ell}} \to |F_j|^2e^{-\varphi}.
\end{align*}
These functions are non-negative and measurable, so [Fatou's lemma](/page/Fatou%27s%20Lemma) gives
\begin{align*}
\int_{\Omega_j} |F_j|^2 e^{-\varphi}\,d\mathcal{L}^{2n} \le \liminf_{\ell \to \infty}\int_{\Omega_j} |F_{j,k_\ell}|^2 e^{-\varphi_{j,k_\ell}}\,d\mathcal{L}^{2n}.
\end{align*}
Using the uniform estimate for the right-hand side yields
\begin{align*}
\int_{\Omega_j} |F_j|^2 e^{-\varphi}\,d\mathcal{L}^{2n} \le C(D,R) \int_H |f|^2 e^{-\varphi}\,d\mathcal{L}^{2n-2}.
\end{align*}[/guided]