Most of quests are taken from a place where "the Joomla version is not supported anymore", as you already noticed. But I tried to merge and organize this mess to something more usable.
Here some links that can be useful for modders: Darkstone QuestEditor (see screenshot) - modified version of Darkstone QuestEditor. The official tutorial - a copy of the official tutorial, I belive.. Original style and design are preserved.
Use this link if you want to copy, edit or comment something in the spreadsheet above.
If you want to share a custom quest, add a comment (with a link to your mod) to Disqus below. You can use Google sheet above too.