It is not fixed on translatewiki, see: https://translatewiki.net/wiki/Wikimedia:Wikidata-mismatch-finder-item-form-progress-bar-aria-label/en (currently showing "Progress Bar indicating loading state when submittion Check Items")

Thanks @Arian_Bozorg. I've added your screenshot to the documentation for this message and for Wikidata-mismatch-finder-item-form-submit (the "Check Items" button).

Also, what is a "check item"?

The link has been removed from the source messages, so this should be closed.

Indeed, it's already sorted

The “problematic” links have been removed from the English originals.

Yes, that's what I meant to convey. It looks like this fix has now been applied, so this issue can be closed. Thanks.

The translated Dutch message had the code changed from the original (from {{plural:$2|{{gender:$4|}}|{{gender:$4|}} to {{plural:$2|{{gender:$4|}}) to avoid the error. Translators should not have to change the code to avoid errors. Not every translator has that skill set, and in any case, the code in the original should be correct and usable as is.

FYI, in my case, the page is not only not updated, but all existing translations revert to English.

In T270854#6772362, @Ata wrote:

The latest {{PLURAL:$1|version of this page has|versions of these pages have}} been marked for translation.

There is no obligation for translations to use PLURAL in the same format as the English original, they can use it in whatever way they need to generate correct grammar in the target language.

In T270854#6712643, @Tacsipacsi wrote:

If they don’t share a single latest version, why does this message mention one “latest version”? Why isn’t it

The latest versions of these pages have been marked for translation.

?

See here for explanation and more examples: https://www.aje.com/arc/editing-tip-subject-verb-agreement-across-prepositional-phrases/

You're quite simply wrong. The prepositional phrase ‘of these pages’ is removable and is irrelevant for subject-verb agreement.

@Reedy, the very page you are citing proves that "has" is the correct form, because "version" is a singular noun. "The latest version have been marked" is wrong.

Also consider whether:

My English is not native, but native speakers (including my partner) tell me it's pretty close. Yet I didn't find these terms intuitive in the least. The moral of the story is, if users with above-average English require a dictionary to use your software, you're doing it wrong.