Since you can pass types to compile-time functions, yes that is correct. Take the example [from the 0.6.0 documentation](https://ziglang.org/documentation/0.6.0/#comptime) for example: At compile time the compiler has to figure out whether to type the `max` function using `u32` or `f64`. Since you can make the boolean condition arbitrarily complex the _type_ of max function called is undecidable in general.
I'm not arguing for or against undecidability in type systems, the page aims to be present the information neutrally.