I'm thinking of a (La)TeX myself, but more in the lines of eXTeX[0], as it is wirtten in Java. [0] https://github.com/tex-other/extex/tree/master
The LaTeX kernel requires some primitives [0] that are unlikely to be supported in a 15-year-old engine, so you probably won't be able to use any version of TeX Live newer than TL20.