...the courts did not rule that. Most courts -- including the U.S. Supreme Court -- simply did not rule at all on the legal, constitutional or factual merits of the cases in question. Not that it's the role of the courts to "disprove" anything, but nothing alleged by the right/Trump, etc., has been "disproved" by any of these court cases despite what many on the left claim.

Most courts simply refused to hear the cases in question. Trump has an election contest case filed in Georgia that never even had a fucking judge assigned to hear it. Some cases are still pending. In the Texas v. Pennsylvania case, you literally had 18 states suing another state on constitutional grounds, including disenfranchisement of tens of millions of voters. If the USSC isn't going to hear that case, who is? And what other case could possibly be more important to take? To say TX and the other states have no "standing" in a matter like that is absurd. If you don't have legal standing to protect your constitutional rights, then you have no constititutional rights.

I agree with you that these issues can be open to interpretation, etc. Nobody really tries to be nuanced on this board -- it's just rhetorical combat to the death -- so I'm not going to hedge my comments as I might if I were in a different forum. While I may not seem like it, I do try to understand the competing points of view, but I'm just going to make my case as strongly as I can and leave it up to those with competing points of view to do the same.

With that said, I'll lay out some the crux of the argument, and you can take issue where you see fit:

-- The U.S. Constitution states that election processes are to be determined by the state legislatures. This is so because, of the three branches of government, legislatures are closest and most responsive to to the people's will, so naturally they should have primacy over elections.
-- In the case of the 2020 election, numerous state laws passed by the legislatures regarding mail-in ballots (e.g., who is eligible, signature matching/witnesses, curing, deadlines, segregation, record preservation, etc.) were violated by election officials, courts, secretaries of state and governors. In some cases (e.g., PA), the state laws themselves were unconstitutional. Thus, those elections were conducted in violation of both the law and the constitution, IMO and according to the legal filings.
-- I don't even think any of this is in dispute, broadly speaking. There are excuses given as to why these changes were permitted (e.g., COVID), but I'm not aware of anyone making a good-faith argument that the legislatures and/or constitution weren't, in fact, voided.

The larger point, though, is why would one party go to the trouble of filing all these preelection lawsuits -- in specific targeted swing states -- to weaken election integrity? There's only one answer, IMO. That they've done everything imaginable on the back end to prevent an audit just adds more evidence to the case.