Fundamentally speaking, this is the exact same problem as Episode L. Lack of straightforward display of episode titles causes this error, and these episodes are the embodiment of said error (i.e. lapse in judgment).*
Episodes such as Episode XL ("Jack vs. The Ninja") and Episode XLVIII ("Jack vs. Aku") technically qualify as well due to the wiki writing "versus" instead of "vs.", but I am willing to let them slide.
At any rate, Episode XXI is "Jack and the Dragon", and Episode XXIX is "Couple on a Train"
"Jack and the Farting Dragon" (and the titular "Farting Dragon" [as opposed to just "Dragon"]) and "The Good, the Bad, and the Beautiful", as titles, are just as fraudulent in design as "Tale of X9".
Ah, it's been a while since I was on this wiki. To be honest I'm not exactly sure what the "real" names of some episodes are. Is it possible that some episodes have different titles depending on what region they aired in?
It seems unlikely. The official sources (CN Asia, CN Australia, iTunes, Amazon digital downloads, DVDs dated from 2006, etc.) are all pretty consistent. Looks like the names that propagated throughout the fandom have been corrupted at some point, independent of the actual titles; the faulty names can apparently be traced to either ToonZone or an early pirated DVDrip that circulated on BitTorrent. (This kind of thing was extremely common in the early P2P days.) There are a few others, like "Jack vs. the Five Hunters" as well.