So e12e is making an argument for XML-y over Lispy. However, choosing good words is really, really hard. If you pick a different word for each construct, there's a needless mental burden; if you pick a uniform strategy ("end-<kwd>") you potentially get less readable code. And either way it's far more verbose, as you point out.

Some of our target audiences are middle- and high-school students, some of whom have weak typing skills (we know from numerous workshops we run). Increasing even the raw number of characters is a real problem for them.

My preference is to use ; for one-liners, but end where you have a multi-clause entity and you want to be able to clearly tell where it ends. If we find that there is general agreement on this, we can make it a context-sensitive check, à la indentation. Then, a program generated by a tool can do something consistent and ignore all these checks, whereas human-facing environments would enforce them (by checking or correcting).

As for your examples, to my Pyretical eye, the third of your examples (with the dangling ";") looks just wrong. However, your fourth example is syntactically incorrect.

I certainly understand this argument, and I generally favour simple syntax over smart tools -- but how much of a difference would this make in an editor/IDE that automatically inserts the closing-tag? (you type case, the editor appends esac (but below the point you're typing)):

    1:   |   #your cursor at |

    2: case|
    
    3: case:
         |     # you hit enter or something, ready to fill in
       esac    # editor has closed block/statement

When editing/copying, it's not typing skills but editing skills, which are arguably subtler and even harder.

It would be a shame to compromise the design of an interesting language just because the target audience is not clearly defined.

All of these are educational audiences. I don't see how one can define the audience more clearly than that, given that I have no control over any of these audiences.