It's funny~ That's all there is to it. I never bothered with doing it myself, but I like reading April Fools chapters that other translators release. Sometimes people even make threads compiling all April Fool releases they can find, so as to make them easily accessible for anyone looking for the joke chapters~ That's all there is to it. It's funny and harmless, so might as well have some fun~
Was a way bigger thing a few years back, with way fewer novels and translators here, but they used to be so ludicruous you quickly recognized them. They posted the actual chapter day after or so, and either kept or deleted the april fools chapter afterwards. Then I think they started demanding markings to show it as April Fools. I personally haven't paid attention the last few years , so I couldn't say how many actually do it anymore.
No greater entertainment than the soul crushing disappointment in realizing the new release of your favourite novel is actually fake.
Another way to look at it, your translator just gave you an original work of their own that you and all the readers can share a bit of amusement about (like watching others fall for it, or enjoying the jokes inside the fake chapter, or theorizing about what the story would be like if the events were true), and the new real chapter will probably come tomorrow. One year there was a chapter where the mc got genderbent and the reactions of the other characters that the translator wrote were pretty believable and ridiculous at the same time. PrinceRevolution's April fool chapters are usually like that. There are some places that it's a bitter thing instead 'haha you thought chapter, but no chapter' and give nothing instead. That's just disappointing. Is that what you're thinking of?
Unfortunately I speak of the links to blank documents, translator originals are fun and I usually don't mind though, I'll treat it as extra entertainment
Thankfully it's not as much of a thing as it used to be and backlash has made translators taht DO do it at least not be lazy and clean up afterwards. I remember for a while there was a problem with some translators releasing joke chapters, labeling it like a legit chapter, and just leaving it like that forever. It was REALLY annoying when bing reading a new series I found and suddenly out of nowhere the main bad guy suprise attacks the MC and it's well written enough that it takes a few paragraphs to notice it's a prank chapter. Serioiusly it's fine to have fun but clean up after yourselves translators. No one's going to laugh at your "prank" in August. You can make a post, you can also delete a post. So just keep things clean.
It's okay, you're not a bot but a lizard. We've known this for years It really does bring a tear to your eye dont it