I've been thinking that for advanced programmers, we really need a few different guides that take advantage of what you already know. For example, a Ruby programmer is going to come to Rust with quite a different perspective than a Java programmer, who comes to Rust with a different perspective than C++.
I don't think that means we need to have one guide per language, but a guide that makes sense to people with a scripting language background (Ruby, Python, JS, Lua), another for people with background in a 90s-era typed language with GC (Java, C#), and another for people with background in a "zero cost abstract language" (C, C++) would cover a lot of ground.
Also, instead of trying for full coverage of all languages, we could have shorter guides that cover less ubiquitous features of specific languages. For example, we could write a document that helps a Go programmer understand errors in Rust, a Ruby programmer understand traits from the perspective of open classes and refinements, or a Swift programmer understand Option from the perspective of nil and forced unwrapping.