[Verginius Rufus]

So if the ERA had been ratified, it would have been the 27th amendment and the current 27th would have been the 28th.

At one point Congress did (illegally) extend the deadline, but that didn't help. Thank you, Phyllis Schlafly!

[Publius]

So if the ERA had been ratified, it would have been the 27th amendment and the current 27th would have been the 28th.

Correct.

At one point Congress did (illegally) extend the deadline, but that didn't help.

Correct again. Congress used the Legislative Process, rather than the Amendatory Process in Article V, to extend the deadline by 3 years, but a federal court struck it down. Some articles on this subject name the drop-dead date as June 1, 1982, but the real date on which the ratification window closed was June 1, 1979.

Attempts to execute belated ratifications were simply virtue signaling. Even Ruth Bader Ginsburg said that if this issue came before the Supreme Court, she would have to hold her nose and vote with the conservatives.