That just seems like an even greater nightmare to me. Soon you would have to learn to read and understand a custom program in a Turing-complete language for each and every installation.
The proper solution is a DSL, just a better DSl. Or perhaps a DSL embedded in something like dhall <https://dhall-lang.org/>, but definitely not a general-purpose programming language.
Tcl is meant to be embedded for scripting and it can be made non-Turing complete by stripping away all but the bare minimum of commands. There is a built in mechanism for sandboxing untrusted input. If can easily be a safe, bullet proof configuration language.
I was gonna consider including Dhall in my list, but then again nginx configuration has support for if statements.
And from my past experience with HCL, sometimes a proper embedded programming language is better than whatever crazy DSL some developers can envision (see for loops in HCL)
The proper solution is a DSL, just a better DSl. Or perhaps a DSL embedded in something like dhall <https://dhall-lang.org/>, but definitely not a general-purpose programming language.