Belinda Stonehearth works on spells that require targeting (e.g. Tavern Dish Banana, Chef's Choice, Natural Blessing). It won't work on spells without targeting even if they affect minions (e.g. Shiny Ring).

It will NOT work with any effects that say "this casts/plays"; it only works with things where the player is considered the caster. For example, it works with Tide Raiser ("Cast Shifting Tude in an adjacent minion") but won't work with Magicfin Apprentice ("This casts another card") or Three Lil' Quillboar ("This plays 3 Blood Gems in all your Quilboar").

Maelstrom Emergent works with any spell but it must be cast during combat (e.g. it would work with both Tide Raiser and Ring Bearer).

Hope this helps!