In T393656#10804189, @NicoScribe wrote:

So the backfill jobs have been run several times to repair the following cases. Do you have logs showing the cause, when a backfill fails?
1 account for https://meta.wikimedia.org/wiki/Special:CentralAuth/Jenikipedia
2 accounts for https://meta.wikimedia.org/wiki/Special:CentralAuth/Furkan2525
2 accounts for https://meta.wikimedia.org/wiki/Special:CentralAuth/Nisapro
2 accounts for https://meta.wikimedia.org/wiki/Special:CentralAuth/Robertlanelilly
2 accounts for https://meta.wikimedia.org/wiki/Special:CentralAuth/Robertlane2031
2 accounts for https://meta.wikimedia.org/wiki/Special:CentralAuth/Fjshuxicjeb1
2 accounts for https://meta.wikimedia.org/wiki/Special:CentralAuth/BobDobolina1

In T393656#10812030, @ArielGlenn wrote:

https://phabricator.wikimedia.org/T378401#10307273 for more about the backfill script and what it skips when doing autocreates; this can be revisited if appropriate.

In T393656#10804485, @Tgr wrote:

Maybe we should pass UltimateAuthority as the performer for the backfill script. Not 100% sure about meta, but at least on loginwiki I imagine we'd prefer the account to be created, even if it's blocked or prevented by some other rule.

In T393656#10813439, @Tgr wrote:

I think this is ultimately a question for stewards, as they are the target audience for these autocreations: when a user registers successfully on some wiki, but their local account on metawiki and/or loginwiki cannot be created because of some local rule (block, abusefilter etc), what would be your preferred outcome for the backfill script (T371267: Create a script to backfill missing local accounts on loginwiki/metawiki for new global accounts)? Obeying the rule or overriding it and creating the account anyway?

In T394733#10837041, @Tgr wrote:

In T393656#10804485, @Tgr wrote:

Maybe we should pass UltimateAuthority as the performer for the backfill script. Not 100% sure about meta, but at least on loginwiki I imagine we'd prefer the account to be created, even if it's blocked or prevented by some other rule.

In T393656#10813439, @Tgr wrote:

I think this is ultimately a question for stewards, as they are the target audience for these autocreations: when a user registers successfully on some wiki, but their local account on metawiki and/or loginwiki cannot be created because of some local rule (block, abusefilter etc), what would be your preferred outcome for the backfill script (T371267: Create a script to backfill missing local accounts on loginwiki/metawiki for new global accounts)? Obeying the rule or overriding it and creating the account anyway?

Yes the backfill script should create an account on loginwiki, even if the account's IP is globally blocked (that's typically the reason why an account is created on meta but nowhere else, e.g. https://meta.wikimedia.org/wiki/Special:CentralAuth/Marx.Elon.Wu). Without a loginwiki account there's no way for stewards to perform CU unless they also hold CU permissions on metawiki. That's especially true now that T394732: backfillLocalAccounts.php does not (always?) copy checkuser data is basically fixed (except for MediaWikiAccountBackfiller appearing in CU results T394732#11612502).