You might have better luck finding a US release. This Amazon listing is sold out, but it'll give you an idea of what to look for if you want to a try ebay

https://www.amazon.com/Batman-Beyond-Movie-Return-Two-Pack/dp/B0002WZS6C/ref=sr_1_fkmrnull_4?keywords=batman+beyond+return+of+the+joker+uncut+dvd&qid=1551581694&s=gateway&sr=8-4-fkmrnull

The censored version had a black plastic clasp on the side and the artwork took up the whole case. The uncut version had a black frame around it with a very prominent "Original Uncut Version" or something to that effect at the top.