Achievement sound replacement
 

Hi guys. Tell me, please, is there an addon that replaces the sounds of achievements with sounds from world of warcraft?🙃

https://www.esoui.com/forums/showthread.php?t=9865

As the sticky post is titled you're supposed to read that post before you ask a question. Point number 3 already answers your question.

Hmm, isn't the achievement sound related to the UI?

Zomg no: https://www.esoui.com/forums/showthread.php?t=1498

I understand you, it's a pity that for 8 years they haven't given such an opportunity.🙃

Yes the achievement sound is replaceable, as it belongs to the SOUNDS table afaik, but not with external sounds! No custom sounds at all :-)
I'm glad they haven't opened for custom sounds as this would open up for possible security issues like virus, beside the annoying custom sounds spread all over the game where you would search where it comes from.
Custom sounds are something for other type of games Imo.