LLM's on their own might fail, but coding agents will succeed because they will be able to write scripts which simulate the states correctly.

You're right that it's worth considering in the same way as the letter counting tricks, since coding agents can get around that in the same way. But I would say the letter counting has the advantage that it at least is easy for humans.

I am just as interested in making the language hard for LLMs as for LLMs+coding agents though.