This kata suffers from the same kind of problem as the other version that got retired: Secret rules that aren't mentioned in the instructions and cause the user's submission to fail with a deceitful rejection message. If it's like the other version's problem where the user is secretly obligated to begin their code with an arbitrary expression that contains explicitly forbidden characters, that's doubly bad.

solution.startsWith('manualCondition = (a, b, c, d, e, f, n) =>') && !['if', '=', '<', '>', '&&', '||', '!', '?', ':', ',', '\\']

You disallow , without telling us ?!? :O

Also, I normally take out those spaces in the arguments.

You really, really have to be very careful to specify things if you don't want to just make it terribly frustrating and effecively a mind-reading exercise. Which it is, now.

The description is still unclear on what is and is not forbidden.

?:!&|{}<>=,

Is it & (bitwise operator) or only && (logical operators)? Is it | (bitwise operator) or || (logical operator) only? Is it ===, or == (comparisons) or = (variable definition, or whatever it's called) in the whole?

I know these from seeing the tests, but should other users attempt your kata only to understand what limitations you try to enforce?

Allowing square brackets was a mistake.

Your katas are identical. I can see that your solutions for them are different, but with a correct approach (like mine or Unnamed's) it doesn't matter whether there're 2, 3, or infinite amount of arguments - it will always come down to copy-pasting the same piece of code for the right amount of inputs.