Isn't that the Prologue/Side Story?
It does look to be the only other game mentioning Artemis Pearl by Triangle!. And the main characters appear to be Red Hair and Blonde Hair in this.Maybe? It's the only other "Artemis Pearl" title I could find references to. I'm not familiar with the series.
No, haven't played it. BUT IIRC there's only three types of content that's banned on this site: sexual content involving pre-pubescent children, IRL gore and IRL bestiality. And since the game doesn't feature real porn images, the list of what it could be is rather short.
As for why it was banned I highly doubt it was rule 7. Skimming CGs elsewhere doesn't appear to be anything remotely close to either shota or loli shit. (and obviously yeah no rule 10 stuff either). I will note there is a possible link to a DL of the translation in the signature of the guy requesting to post it that still looks to be active. Not sure if just a translation patch as 2 GB is quite a large translation patch. But this game is also very large.Any idea what the banned content is? That just makes me want to play it more.
As for how much you'll gain from the earlier one: From the prologue/chapter 1 of this game, it seems not much is lost by just playing this one. You'll probably miss some references, but the MC of this game is an alchemist who appears missing from the the pirate one. So likely standalone-ish unless you really care about those extra tidbits of references and lore. (In some aspects it may be better to play this one without playing the first in case the first provides answers to the questions raised early in this game)