There were so many before (SILE, Patoline, Rinohtype, ...)
Why not just use LuaTeX, either directly with Lua as a typesetting language, or with a custom language transpiling to Lua or compiling to Lua or LuaJIT bytecode?
Here is a solution based on LuaTeX: https://www.speedata.de/en/
Compiling to LuaJIT bytecode is not that difficult (see e.g. https://github.com/rochus-keller/Oberon and https://github.com/rochus-keller/LjTools).
If it's primarily about a better typesetting language based on TeX, then we already have e.g. https://en.wikipedia.org/wiki/ConTeXt.
There were so many before (SILE, Patoline, Rinohtype, ...)
Why not just use LuaTeX, either directly with Lua as a typesetting language, or with a custom language transpiling to Lua or compiling to Lua or LuaJIT bytecode?
Here is a solution based on LuaTeX: https://www.speedata.de/en/
Compiling to LuaJIT bytecode is not that difficult (see e.g. https://github.com/rochus-keller/Oberon and https://github.com/rochus-keller/LjTools).
If it's primarily about a better typesetting language based on TeX, then we already have e.g. https://en.wikipedia.org/wiki/ConTeXt.