Sphinx's Insight

• WWizards of the Coast2024-01-12
  Official Ruling
  Addendum abilities of instant spells apply while the spell is resolving, not immediately after casting it. If the spell is countered, you don't get the addendum bonus.
• WWizards of the Coast2024-01-12
  Official Ruling
  If an effect copies a spell with an addendum ability while it's on the stack, the copy wasn't cast at all, so you won't get the addendum bonus.

Rulings via Scryfall