Like any transpiler, Sucrase can be run in parallel by having the build system send different files to different threads/processes. Sucrase itself it more of a primitive, just a plain function from input code to output code.
> What I do not understand is "Sucrase does not check your code for errors." So it's not a type checker?
That's correct, Sucrase, swc, esbuild, and Babel are all just transpilers that transform TypeScript syntax into plain JavaScript (plus other transformations). The usual way you set things up is to use the transpiler to run and build your TS code, and you separately run type checking using the official TypeScript package.
> What I do not understand is "Sucrase does not check your code for errors." So it's not a type checker?
That's correct, Sucrase, swc, esbuild, and Babel are all just transpilers that transform TypeScript syntax into plain JavaScript (plus other transformations). The usual way you set things up is to use the transpiler to run and build your TS code, and you separately run type checking using the official TypeScript package.