How to conjugate the verb in a sentence that starts with "I wish..."

Solution 1:

First off, you shouldn't have a comma after wish. In written English it's generally incorrect to add a comma before that or in a place where that has been omitted, as in the previous sentences.

Either of these is correct:

I wish the documentation warned about that limitation.

I wish the documentation had warned about that limitation.

In either case, you need a subjunctive form (which is almost always identical to the past form) in the subordinate clause. The main clause with wish should remain in the present tense — saying I would wish is unnecessary.

(The only time that the subjunctive is not the same as the simple past is when the subject is 1st- or 3rd-person singular:

I wish I were taller.

I wish it were true.

And even this is slipping away, as many people now say I wish I was taller.)