Qemu works by translating a binary to an IR then doing stuff with it. Valgrind likewise. There's an optimiser called bolt (associated with facebook) which has the same idea.
Yup, I'm aware of both of those, but none of those tools listed so far are intended for the IR to be for human-consumable unlike disassemblers and decompilers. You think disassembly is verbose compared to a decompiler? Go look at the equivalent Vex (Valgrind's IR) for any non-trivial disassembly. It's suuuper verbose.
As far as I know, BNIL (https://docs.binary.ninja/dev/bnil-overview.html) is the only one that is designed to be readable and it still wouldn't make sense to include it in an IL comparison such as the one done here for decompilation in my opinion.
