Though I mostly agree with what you say about Janet, I think considering Janet the spiritual successor is a far-fetched statement. I would advise you to have a look on niiLISP (Newlisp on Rust) which is a direct dialect of Newlisp. Eshkol is also quite Newlispy (most 'new' Scheme's are, anyway). I guess choosing a programming language which looks Newlisp-like is a matter of personal taste (I love Carp). But if what you are looking for is an updated version of Newlisp, with all its syntax and architecture (ORO, etc.), then Hyperlisp-Sintaxial is the one to go. Hyperlisp is Newlisp on Dlang, with all Newlisp functions and libraries (modules) hardcoded in native D, plus some new 500 functions (stochastic analysis, fractal analysis, cryptoanalysis, the entire Arguelles's fuzzy functions enhanced and recoded, neural network activation functions (elu, relu, leak-relu, mish, etc.), and native math library expanding GSL math library. No external libraries are used, though it incorporates FFI (it is Newlisp, anyway).
The cons is Hyperlisp is propietary software (not commercial), mainly use for strategy war gaming, cryptoanalysis. and signal processing. All in all, niiLISP is what you should consider the closest available new-Newlisp you can have access to.
The cons is Hyperlisp is propietary software (not commercial), mainly use for strategy war gaming, cryptoanalysis. and signal processing. All in all, niiLISP is what you should consider the closest available new-Newlisp you can have access to.