I had a few ideas for accessories, so I'll write em down.
You know, as much as this mod already adds a lot of ballons... I still think you can add one last one! In hell, in Shadow chests, you could make it possible to find "Flame in a Bottle". Which would be another jumping accessory that can be eventually crafted into it's subsequent balloons. I know it doesn't make sense to have fire inside a balloon, but I'm pretty sure having a Blizzard or Sandstorm inside it doesn't make much sense either.. I know there are already a lot, but I think the Giant Balloon bundle is missing an Orange/Red color into it, and an extra jump never hurts, does it?
Frostburn/Poison/Venom/Ichor/Cursed Flame Gauntlets/Stones. DoT's in Terraria really do help in killing enemies, so why not make a few extra enemies drop stones in some of their respective biomes? Frostburn would obviously be in Ice, Poison in the Jungle, Venom could be Spider Nest, Ichor from Crimson and Curse from Corruption. These could all be made in a gauntlet or another piece of accessory that gives you attacks that property, and later on be combined into an ultimate accessory that gives it all (assuming you actually have the patience to go around each biome to collect low drop rate items and combine them with a lot of other accessories to get it, which is quite hard, and in the end is balanced, since it takes so much effort to get).
Health Version of the many Mana accessories. I feel like this is needed, becuase it doesn't make sense to have all those MP things without the HP ones. I would love to have a heart magnet or something that used potions for me automatically as long as I don't have potion sickness. It's just a little touch that would make a world of difference. The way you get those items could also be close to the way you get the Mana ones: Magnet is sold by Merchant, Flower you get in the jungle, so on and so forth.
Make the Elemental boots jump automatically and swim faster underwater. When you have any accessories that grant you double jump properties, you need to tap space between each extra jump, which can honestly be a hassle. You could introduce some kind of Spring Boots, that mde you jump automatically and then combine it with the elemental ones to make one that jumps on it's own. Some people may not like this idea tho. Also, why not mix the flippers in the recipe at some point so it's possible to swim underwater?
That's all I have, hope I helped!