So are you trying to say that itzy needs another vocalist because their vocals aren't strong enough?
Itzy wasn't made to be a vocal group. Would it have given them a leg up if their vocalists were as strong as their dancers? Absolutely. But that's not what they were meant to be. They're performance-based and (unfortunately) that means that vocals weren't the main focus.
There's plenty of other ggs with strong vocal AND strong dance lines. Some also have fluent English speakers, too.