Fixed

Object is a proper noun in JavaScript, because Object is an object in the language standard. Since all objects inhert from Object, they are technically instances of Object as well. An object in JavaScript is therefore also an Object.

Furthermore, in JavaScript, an array is an object.

Doesn't have any test cases for the less-than-two-levels-down rule. This let me submit an incorrect solution because of a bug in my rank difference function.

The function signature for the java example is all wrong. The function returns an int and the parameters aren't typed, which is a syntax error.

Made it clear that we have 4 specific instructions on this Kata.

Edited description

The default tests are not here to give you the solution, by the way, the null case is explicitly quoted in the subject description.

It takes far too long if you copy/paste each data one by one instead of using a simple regex replace in your favorite text-editor.

The abstract inheritance is here to make sure everyone understood the principle of inheritance.

Kata are supposed to give challenges of many kinds. Here the challenges (depending on your Java level) are mostly within the algorithm and technical knowledge of the library/language.

If the Kata is bugged in some way, you can mark it as "Major Issue" but I doubt the arguments you just said are enough consideration.
If you want a higher level Kata well this one is only 6kyu, you should take a look elsewhere.

Hello!
When I try to submit my solution ( that passes simple test ) I have this error:

fullTest(EncodeTest)
Failed special encoding
Any help??

This is just an incredibly bad kata. It has minor edge cases that trip you up that aren't hand-held in the default tests (the null case).

It takes far too long, because you have to go through the mind-numbing process of copy-pasting every single leetspeak character into some sort of processable data structure. Protip: testing my ability to copy everything into vim to automate repetitive text replacement tasks doesn't help me learn java.

It forces you to use an abstract inheritance in a case that I think is just horribly overengineered (but this is java so I mean, that's an argument, not a complaint). But even then, the abstract class is completely given for you, which makes the thing seem so superfluous.

As far as I'm concerned, Kata are supposed to give me bite-size challenges that help me learn language features, not give me some cool end product. I think, in pursuing that end, this Kata just totally missed the point. I would have marked this as 'major issues' if I had the reputation to do so.