How to read $NC^1\subset L \subset NL \subset SAC^1$, $SAC^1=LOGCFL/poly$, and similar statements?
The source of the confusion is probably uniformity. A circuit class like $\mathsf{NC}^1$ can be defined in two different ways:


Languages computed by bounded fan-in circuits of polynomial size and logarithmic depth.
Same as 1, only the circuits are uniform: there is an efficient Turing machine that on input $1^n$ generates the $n$th circuit.


The definition of uniformity is vague since there are several different definitions, many of them fitting the above description (with different definitions of efficient). The classic paper On uniformity within $\mathsf{NC}^1$ shows that many of these definition are in fact equivalent, and as far as I know, their common definition remains popular today. It often goes by the name "$\mathsf{AC}^0$-uniform".

If you want $\mathsf{NC}^1 \subseteq \mathsf{L}$ then you need the uniform version of $\mathsf{NC}^1$. If you want $\mathsf{NL}/poly \subseteq \mathsf{SAC}^1$ then you need the non-uniform version of $\mathsf{SAC}^1$.