I thought there might be a workaround to use an RSS feed from Elgg to crosspost to Twitter via IFTTT, but this does not seem to be working either.

I can read Elgg Wire posts with RSS on Microsoft Outlook, so that seems to be working but still can't seem to crosspost to Twitter via IFTTT from Elgg RSS.

Our Elgg HybridAuth has crossposting feature.

Currently, crossposting is only available for blogs, but we can add it to The Wire as well.

Using Twitter API is no longer free. So, even if you get the Elgg site to cross-post Wire postings to Twitter, you'll probably need to pay a monthly fee to be allowed to add your postings to you Twitter account. Problem might be if Elgg site users want to add their Wire postings to their Twitter accounts. The would need to pay for Twitter API usage each on their own!!!

And maybe before thinking about (and paying someone for) letting someone updating the Twitter plugin to work on Elgg 4 AND with the Twitter API fees you might consider if you trust Mr E. Musk enough to NOT change his mind tomorrow once more and changing the Twitter API again for not allowing any posts getting added from external sources at all. Or Twitter closing once and for all..

@iionly

Using Twitter API is no longer free

Twitter Standart API is still free (yet).

Problem might be if Elgg site users want to add their Wire postings to their Twitter accounts. The would need to pay for Twitter API usage each on their own!!!

It's not correct. Only the site owner as the Twitter app creator will be charged for increasing the rates limit or using the Enterprise/Premium APIs. Users allow access to their accounts only to Twitter app.
You can check it in this Elgg app.

you might consider if you trust Mr E. Musk

That's right. For these reasons, we suggest that our users use Mastodon instead.

Prices have been announced today: basic package with up to 1500 tweets per months to be posted via API is free. More than that costs at least $100/month.