I say this as a non-expert who has been enjoying writing some Lean recently and has previously also written some Coq and Idris.
The interactive elements really can’t be done justice in looking at readme’s or textbooks alone IMO
I'm sure other solvers (Coq, Idris, etc.) also have online communities where you may be able to ask questions.
Anyway, I think that, at a minimum, at least one class like that should be part of every CS major's education, if it isn't already. That way, proofs are less intimidating, and things like Coq and Isabelle/HOL are less intimidating.
You're probably right about the ship having sailed, though. It's probably harder to get people to learn new things when they haven't been in school for a long time.
The workflow you'd like already exists one to one in Isabelle: You can simply type "nitpick" halfway through a proof and it will try to generate a counterexample in that exact context.
The biggest thing I think these tools are missing out of the box is, basically, "run quickcheck on my proof for me". It's too easy to have some code, and try to prove some property that isn't true, and rip your hair out thinking "why can't I get the proof working!"
If halfway through your proof you end up in a thing that seems nonsensical, it would be nice for these tools to just have a "try to generate a counter-example from here" command that spits out a thing.
Proofs are so path-dependent, and it's not trivial to do in general. But I think they are all very close to greatness, and every time I've gone through the effort to formally verify a thing, it's been pretty illuminating. Just... if you're trying to prove some code, the process should take into account the idea that your code might be buggy.