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A way to keep the party together (without the jester) may be walking into a dungeon and procking a hidden event campaign could also be a thing (where the players have to have a main group together to continue the plot) likely granting a chance at rare items, or at worst locking the party from going to other dungeons until the story quest is complete.

It seems you really want the party to head after the Jester, but at the moment there is far more reasons not to.
As mentioned, some of the persons here minus jaiden since he does work in cybersecurity but would risk being banned don't really have a decent chance to stand up to the guy or away to achieve it which is why Jaiden wanted to avoid conflict with them earlier. The motivation for going after the Jester is a little low.

A simple solution I would see to tie them together would be blackmailing the doxxed players.
Perhaps giving a list of demands, which does force the group to generally stay together, in turn Jaiden receiving an online "bounty" on the guy. The alternative of Doxxing Jaiden would be less likely, and may have his job actively ban him from playing said game in turn for a full investigation
Or corrupting/threatening to corrupt character ID's...

Depending the Jester could be pissed off that they may have not received the artifact, or at least a fully functional one.
As Goibniu's automaton could have damaged or even broken it, which I don't think was noticed. Leading to the Jester needing to manipulate or otherwise hunt down the party again, whilst being looked out for, or needing to manipulate a situation to buy or trade the artifact indirectly from the party. If they try to trade it, they would need to bring something to the table and possibly reveal more of their own motivations.

It'd probably be less invasive to have the Jester be a background or reoccurring threat otherwise. Such as them paying other players to PK the party, and thus making dealing with Jester (or their midway guy) more pertinent. But that's more of a tightrope (don't want to overdo it), because... as a player, that could raise the chances of just, quitting tbh. So it'd have to be annoying but not overwhelming, probably more of a villain of the week type of deal.