S2 episodes available after S3 starts?
Pretty sure the episodes will still be available especially since they’re charging 200 gems per episode if you missed them.
Indeed, so long as you have logged in to the game (not character select, actually into the game) at least once during the time the chapter was active, you will always have access to it on every alt you ever make.
If you have not logged in during the active time, you will need 200 gems per missed chapter to get full access, or get someone who has it unlocked to give you a guided tour sans achieves and rewards.
The episodes/the whole of season 2 stays in game forever. It is permanent content.