The issue here is the mods neglected to provide a name in the title. And so people wind up randomly adopting names they find on the internet. I believe if J-XD, J-XS, or J-XDS was in the title, then whichever name is up there would naturally become standard within this forum. And if becomes standard here, it slowly leaks out elsewhere.
Even though none of those 3 names are official, their use of "X" instead of numbers makes it abundantly clear they are only temporary placeholders. It's no different than the JH-XX or F/A-XX.
That is far better than "J-50" which tricks casuals into believing it's the official name. Literally nobody knows where "J-50" came from. Every person that insists on using that name simply shrugs their shoulder, and say they heard it from someone else. It's a classic example of how misinfirmation spreads. Every person that uses "J-50" perpetuates that poor practice.
And then there's "SHENGAD". The name is perplexing to casuals unless someone explained its history to them (Shenyang + NGAD, and possibly a reference the CHAD meme). I also don't like it because it's shamelessly aping the American concept NGAD. I don't believe any other country uses "NGAD" in reference to their next generation aircraft.