I'm sure you can find something it does a bad job on (have you, though?) but it's done swimmingly on some really horrendous 18th century examples I've found. Among other obvious things, it translates the Revolutionary War cursive that leads off this article.
I think people may be kidding themselves a little bit about this stuff.
I wish! I do genealogy, I would love automated transcription of historical documents. Have I? Oh yes! It wasn't rhetorical that I could find you thousands of pages. Here's one book if you want a link: https://media.digitalarkivet.no/view/166325/4
But every time I find something that I think "This one is surely easy enough!" it's usually wrong. US revolutionary war cursive is on the easy end; it's quite similar to modern cursive, and what is of training data in the datasets is probably a lot like it, if not actually in it - historians who test this complain about overfitting. Which I believe, because as I said, I see that it's bad at generalizing.
I think people may be kidding themselves a little bit about this stuff.