Random, but have anyone ever doubted that the word 'unlimited flow' is a wrong translation? As wrong as *coughquicklywearamaskcough* Baidu has a page on the word and it seems that they provided their version of word in English already - Infinite style (much nearer to the meaning albeit still sounded weird) Link: https://baike.baidu.com/item/%E6%97%A0%E9%99%90%E6%B5%81/5383795
Unlimited flow specifically implies that there's horror, so it's still a bit different from just regular world hopping. And usually, they aren't actual "worlds"- for me, I usually think of them as something closer to a "room" or an "instance." Unlimited flow itself is pretty literal already, and Baidu's translations are often a little... off, so I don't think it's a good source for English translations. I do agree that QWTFOD is weongly translated, though.
I mean. It originated with Terror Infinity, so something like "Infinite Style" (or rather "Infinity Style" imo, meaning "in the style of Terror Infinity") would absolutely be more accurate than Unlimited Flow. Not that I care either way. I think the gist is conveyed well enough.
For me when I first saw the word, I'm like wtf does that even means? At that time, I never read any novel of that genre so...
Doesn't need to, honestly. It's a sub-genre, at best, or a tag. A specific type of story using specific tropes. If you're not familiar with those tropes and aware of what you're looking for, it's an irrelevant classification for you. Some genres/tags are just like that.