[*]Hail of Thorns - summoned thorns sprout from ammunition. Attack does "normal effects" and the thorns do piercing.
[*]Swift Quiver - Specifies the ammunition is non magical and grants attacks
Let's talk specifically about the two bolded.
Hail of Thorns:
(1st-level conjuration)
Casting Time: 1 bonus action
Range: Self
Components: V
Duration: Concentration, up to 1 minute
The next time you hit a creature with a ranged weapon attack before the spell ends, this spell creates a rain of thorns that sprouts from your ranged weapon or ammunition. In addition to the normal effect of the attack, the target of the attack and each creature within 5 feet of it must make a Dexterity saving throw. A creature takes 1d10 piercing damage on a failed save, or half as much damage on a successful one.
At Higher Levels. If you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d10 for each slot level above 1st (to a maximum of 6d10).
For off, this is not an attack within 5e. This is a saving throw vs an effect. It also procs off hitting with an attack which makes it more akin to the paladin's Smite spell. This spell does not grant an attack, it is not subject to the errata or this discussion. It is important to note though that this spell creates a secondary effect on top of whatever "the normal effect of the attack" would be. For example, if you were using a magical weapon to make the attack, it would still be magical and bypass because that would be part of the "normal effect of the attack". Same for if you had some kind of special effects on hitting or dealing damage and so on. So the spell specifies that on top of whatever would happen normally for making the attack you get extra stuff. Bottom line, this spell doesn't help.
Swift Quiver:
5th-level transmutation
Casting Time: 1 bonus action
Range: Touch
Components: V, S, M (a quiver containing at least one piece of ammunition)
Duration: Concentration, up to 1 minute
You transmute your quiver so it produces an endless supply of non-magical ammunition, which seems to leap into your hand when you reach for it.
On each of your turns until the spell ends, you can use a bonus action to make two attacks with a weapon that uses ammunition from the quiver. Each time you make such a ranged attack, your quiver magically replaces the piece of ammunition you used with a similar piece of non-magical ammunition.
Any pieces of ammunition created by this spell disintegrate when the spell ends. If the quiver leaves your possession, the spell ends.
The two attacks granted by the spell via bonus action would bypass resistance and immunity because the source of the attacks is the spell. Just because the weapon you use or the ammo you fire isn't magical doesn't mean that you can't bypass. The errata doesn't care at all for that stuff. All it cares about is what granted you the attack in the first place. Was it a spell, magical item or magical source? OK! You bypass! I don't know when the spell was written, perhaps before the errata was released (BTW I would like to point out that this can also cause some spells you're listing to be weird in light of the errata, they didn't go back and change all the other game elements that would no longer need to specify these kinds of things) which would explain why they felt the need to specify that the ammunition was non-magical. It could also be that the devs simply didn't want the player to be able to create an endless supply of magical ammunition for reasons unknown to us. Or maybe they just didn't want to have to get into what kind of magical ammunition it is, how much bonus damage it deals and so on.. They just wanted unlimited basic ammo. However that doesn't change anything. Post errata the attacks would bypass because they have a spell source.