change SetObjectiveVisible() to SetObjectiveState("armada", OBJECTIVE_ACTIVE)
I made some minor adjustments to the quest in the editor, and everything seems to be working, it's all displayed, activated, but it doesn't register as completed... I'll go look for typos.
update: it's quite strange. It's not a typo, but the quest just won't complete, even though the "kill enemy hero" task has been completed. The "Kind Manual" also won't accept it. Maybe I need an additional trigger for killing that hero, which will complete the quest? But isn't that strange? Shouldn't it just complete automatically? D: