I can not imagine trying to translate system code in this way.
Marc, you are better than that - proof by lack of imagination is not very effective😘
Seriously, the "VAX Compiler" that Paul describes made a great deal of sense to the VMS team when it was developed. It's all about economics, not technical purity. And solution actually worked really well; as Paul points out, it lived for many different ISAs that followed VAX at DEC and now VSi.
What I always was amazed by was the Cutler use assembler in the first place since DEC had production quality BLISS compilers. But as Dave Cane [VAX750 lead] once put it, it was the world's greatest assembler machine. Dave (famously) hated BLISS but was one heck of an assembly programmer. VMS both at the kernel and systems level, was (is) in assembler, so treating the VAX as a HLL and "compiling" to a new ISA was solid economics.