I reckon language choice matters more at the edges of economic activity where a specific language feature really does make the difference in the end product, but most activity that is leveraging LLMs now is more generic enterprise SaaS software.
Go is the perfect language for this new world. Its development loop is fast, it has types but not too much so, it is memory safe, it is easy to deploy and it runs efficiently enough for most line of business use.
Go was originally developed specifically for a world of interchangeable hard-working juniors, which is exactly what LLMs can scale up with only your budget as the constraint.
I'm wondering what advantage a hypothetical faster-compiling-Haskell would have in that world.
That is: Have a Haskell base system. Have a Python "development" version on which you iterate at lightning speed. But also, in the background, moving at whatever pace it takes, have an agent running that imports all the Python development changes into the Haskell version. Have nightly builds of the Haskell version to reap its benefits (issues caught by the type system, more efficient native code). They must have continuous or nightly processes to fix bugs in the Python code anyway, there is no way that all the things they ship "while still on the call with the customer" are always tested on the full test suite and always 100% correct.
And it doesn't have to be Python/Haskell of course. The "development" version could be a (hypothetical?) interpreted Haskell. I have no idea if ghci would be useful for this. Neither do I know if the 15-minute Haskell build time is spent in the frontend (so an interpreter would have to pay that cost too) or in code generation or linking (which the interpreter wouldn't need to care about). Anyway, these are things I would think about before I did what the OP did.