> no `call/kw' prefix and using symbols to introduce optional arguments (so
> that they essentially appear as a plist). Apart from the syntax, this
> is equivalent to CL-style.

You're right. It has the exact same advantages and problems as CL.

> This solves the caller-side of the problem, which is the most visible
> side. For the callee-side, there can be different ways like
> `lambda/kw', `define/kw' and `let-keywords'.

And hygienic keywords can be accomplished by:

(let ((my-keyword something-unique-imported-from-a-library))
   (some-procedure-taking-keywords pos1 pos2 pos3 my-keyword my-value))