I think you are conflating a couple things. First off, the election of electors is not a “federal election.” It is a state election governed by state law. There is a pretty critical constitutional difference between the election of electors and the election of members of Congress: The Elections Clause of Article I empowers Congress to at “any time by law make or alter” regulations for Congressional elections. Congress is given no corresponding power regarding the appointment of electors under the Electors Clause of Article II: the power to appoint electors is delegated solely to “Each state . . . in such manner as the Legislature thereof may direct.”
Texas does not have the right to complain of how Pennsylvania appoints its electors any more than Pennsylvania has the right to complain of how Texas appoints its electors. Pennsylvania, through its legislature, gets to decide how claims of fraud in its appointment of electors are resolved. If the Pennsylvania legislature does not want to adequately secure its elections against fraud, then that is between them and the Pennsylvanians who elected them. They are Pennsylvania’s electors, not Texas’s.
The legislature may be constrained by the Pennsylvania constitution, and that’s one of the arguments currently being litigated (that the legislature’s provision universal mail-in votes violates the Pennsylvania constitution). But Texas is not a proper party to that litigation.
Do we really want states suing each other over how they conduct their elections? What if, next time, California sues Texas because our Voter ID laws make it too hard for minorities to vote, or because we are violating the 14th Amendment by prohibiting illegal aliens from voting.
Using the logic that States have sole rights over electors and elections, like the democrats did after the civil war, leads to blacks only having 4/5th the vote of say a white person.
This was the insanity of the Democrats after the Civil War, and I am certain you remember the SCOTUS ruling that this was a violation of their Constitutional rights. Indeed, conservatives are a minority in many places. Should you only give them 4/5th of a vote, or defraud them in elections, it’s the same violation, just not based on skin color.
Your argument that State’s can ‘do what they want’ failed in the post Civil War America. Race, Sex, Ideology, doesn’t mean you don’t have equality. So yes, I believe that they have a rock solid argument for the SCOTUS because they are ‘trapped’ by their previous decisions empowering minorities after the Civil War.