To my knowledge, those cases so far have been in state courts. I limited my discussion to federal courts, which are the only ones that can rule on this issue.
I also believe Cruz can get a hearing on several court filing if he had the balls to file them given the current impact this debate is having on his campaign.
What you believe and what the law says are 2 very different things.
The Schwartz case was filed in a federal court. He lacks standing.
State courts have an interest in ballot integrity, and can remove unqualified candidates from the ballot. If that is improvident, the candidate can take the issue to a federal court. Well, he can take it federal court, improvident or not - the argument is that the removal was improvident.