Base Class: Ranger
Attempt to make the arcane archer good. Prerequisite: Archery fighting style.
This is an Arcane Archer build. Not being an archer would be counter intuitive.
Spell Shooter
Starting at 3rd level when you cast a spell using a ranger spell slot you can choose to fire it like an arrow from your bow. You can choose to replace the range of the spell with the range of the bow. You still use your spell attack modifier if the spell requires a roll to hit (The DM may or may not choose to make you roll regardless). The spell still behaves as it would once it reaches it's destination (Example: Cure Wounds would heal the intended target). Yes... this means you can heal your friends by shooting them in the face.
Bonus Cantrips
Starting at 3rd level you gain the cantrips Light and Message.
Magic Arrow
Starting at 7th level your arrows count as magical for the purpose of bypassing magical resistance.
Elemental Arrows
Starting at 7th level you gain the ability to infuse your shots with elemental energy. When you take the attack action you can choose to infuse one arrow with either cold, fire, or lighting damage. Doing so replaces the arrows damage with the chosen type. The elemental energy does not remain after the shot is expended. You can do this a number of times equal to your ranger level. You regain all expended uses after a long rest.
Piercing Arrows
Starting at 11th level you gain the chance to pierce your target. If you roll a critical hit on a target you can select a second target provided on is in the path of the arrow. Make an additional attack roll to hit the second target. This effect only works once per arrow.
Eternal Archery
Starting at 15th level you are no longer limited by petty things like ammunition. You are able to fire bolts of magical piercing energy from your bow that mimic the damage of firing a real arrow. This ability work with your Elemental Arrow ability granted at level 7.
https://www.dndbeyond.com/subclasses/974331-arcane-archer-nex-edition
It is version 0.5. Still needs work.
I don't feel that the Ranger spell list really supports your Spell Shooter feature. And a good number of them get really confusing, such as Zephyr Strike or, indeed, Lightning Arrow.
Light and Message are nice but without some explanation I can't see why this subclass is getting them specifically.
Elemental Arrows seems underwhelming. All it does is bypass nonmagical damage resistances (not nothing, but not very exciting) and exploit the barely existent damage vulnerabilities, so frankly I see no reason to limit it to once per turn or to a number of times per rest, both of which you've done here. You could remove those limits or even make it stronger and it would still be fine.
As odd as it sounds, I think your instinct to change the Curving Shot to Piercing Arrows is correct. Curving Shot is stronger, but nobody wants a feature that only works when you're losing, and that's what it reads like. This one's more proactive, or it seems to be. This would also give the Ranger a reason to move around, which is great.
Eternal Archery is extremely lame. This literally does as close to nothing as you can probably get. Great for those scenarios where your level 15 character gets captured and his arrows are taken but not his bow, though. :P