In russian i think these are words that have many letters е,я,ё,ю, бесперспективный f.e.
I speak Russian for a while and I've learned it by myself, and those letters were my favourite letters, the words with them were great, I think щ is much harder, because you don't have an equivalent in English, German etc.
Some Polish for you 🙂 Chrząszcz brzmi w trzcinie / Jan Brzęszczyczykiewicz / Stół z powyłamywanymi nogami / 1999 - tysiąc dziewięćset dziewięćdziesiąt dziewięć / Dżdżystym rankiem gżegżółki i piegże, zamiast wziąć się za dżdżownice, nażarły się na czczo miąższu rzeżuchy i rzędem rzygały do rozżarzonej brytfanny / Konstantynopolitańczykiewiczówna wśród Szczebrzeszynów, szła suchą szosą do Konstantynopolu.
kisses from poland 🙂🙂
For non-Germans, the hardest word to pronounce is still "Streichholzschächtelchen" oder "Eichhörnchen" 🙂 Try it and tell me if you were able to pronounce it correctly 😁
Well I’m not gonna tell you a « german » word since I am from Austria where many different dialects are spoken. Whenever a foreigner happens to visit the region where I live, he has to pronounce « Oachkatzlschwoaf » at least once. Good luck.