https://translatewiki.net/wiki/Category:Pages_with_too_many_expensive_parser_function_calls has 10 pages currently.

Sorry, I do not understand what this issue is about. Can you clarify? As general note, issues related to content on the wikis are out of scope for Phabricator.

Lacking information on which MT engine and tool this task refers to. But even if we had that information, there usually is nothing we can do about the output of MT engines.

Deployed one version ago.

@wormgirl Are you still working on these things and interested in getting to translatewiki?

No update, not actionable.

Looks done to me. Please reopen with details if I am wrong.

https://www.mediawiki.org/wiki/Extension:OATHAuth doesn't mention the requirement of gmp or bcmatch php extension that is mentioned in https://www.mediawiki.org/wiki/Extension:WebAuthn. Should it be added or is it outdated?

I've not seen any stack trace that points to l10n cache. Only Translate's message group cache. Either version of codebase should work fine, but not when migrating one version to another or two codebases sharing the same cache value. In addition, there might be multiple cache values, one for each datacenter.

1. We do have (in)formal variants for de, hu and es as well.
2. This thing has existed for over 15 years. Removal would need a better reason than "I don't understand".

For Translate, running createMessageIndex.php should regenerate caches. I am not sure if anything else is impacted.

Essentially same as T415619: Creation of dynamic property MediaWiki\Language\Dependency\FileDependency::$filename is deprecated {"exception":"[object] (ErrorException(code: 0) but this one is for WMF production. Translate extension is just a casualty here.