I can transfer funds from my Finnish bank account to my German bank account and I get a push notification from the German one within seconds of submitting it. If your SEPA transfers aren't instant, it just means that one or both of the banks involved haven't just adapted it yet.

Banks might also have only implemented receiver or sending, but not both. My mom can receive my instant SEPA transfers, but she can't send me one back since her bank has only implemented the receiving part.

The SEPA Instant Credit Transfer scheme introduced in 2017 introduced 10-second transfers. Not all banks are participating yet, particularly in (south-)eastern Europe, but it's a fast growing share, and in my home country (the Netherlands) just about everyone does.

All of my SEPA transfers after 2017 took days and none of them involved banks in (south-)eastern Europe. But it's good to hear that things are improving.