With the current changes to party sync asynchronous completion of quests is not possible if users are not all online as intended, however, this means small private servers must alter their playstyle to keep synchronized.

One method to get around this issue is to complete quests manually for more sporadic users. Quest completions in this manner do not consider the many chains of quests often used in modpacks and only completes the intended quest instead of all quests leading up to that quest.

An option to recursively complete all quests that lead up to the intended quest would be a nice feature to include especially because a proper config is still in the works.