I only found a link to the Central Bank of Ireland but it refers to the legal requirement to accept all IBANs from all European countries instead of insisting on a local IBAN. The whole point of the SEPA regulation is to remove borders and barriers to allow consumers having a bank account in any member state and using it across Europe.
In Ireland, VHI health insurance didn’t accept my German IBAN until I told them about legislation. As far as I know, they only put my specific IBAN on their whitelist but still show that customers have to use an Irish IBAN. The same happened with a few other companies in Germany and Ireland and from what I can read pretty much everywhere. They discriminate against their (potential) customers, they break European law and the lawmakers don’t really tackle that issue and fine companies to my knowledge.