For some reason, SIMD and FFI initially got mixed up in the “Panama” thing. They have since split the JEPs, and FFI has landed by now while SIMD still has some teething pains.
Python is the obvious competition for “painful FFI”, and C for “painful SIMD”.
I think julia is only mentioned for GPU because there is no widely popular language that makes GPU painless.
I think they should also have mentioned Lilliput (“object headers are too heavy”).