"Couldn't stick to the ABI ... despite CPU manuals being available" is a bizarre interpretation. What the article describes is the generated code being too large. That's an optimization problem, not a "couldn't follow the documentation" problem.

And it's a bit of a nasty optimization problem, because the result is all or nothing. Implementing enough optimizations to get from 60kB to 33kB is useless, all the rewards come from getting to 32kB.

IMHO a new architecture doesn't really make it any more interesting: there's too many examples of adding new architectures in the existing codebases. Maybe if the new machine had some bizarre novel property, I suppose, but I can't come up with a good example.

If the model were retrained without any of the existing compilers/toolchains in its training set, and it could still do something like this, that would be very compelling to me.