I said the problem with pathfinder lore is that all the constructs and undead already have souls and are already target-able with trap the soul and so on.The intent of blue magic was to provide the occasional bonus spell after fighting enemy wizards. Though, come to think of it, if a sorcerer was willing to spend the money, they could just buy up a bunch of scrolls and cast them on himself to get all the spells he'd want. I'm thinking of adding the following restrictions to prevent this sort of abuse. First, the learned spells cannot come from scrolls, wands, staves, or other items. They must be cast directly by another spell caster. Second, the learned spells must be encountered in combat against a hostile foe (no paying a wizard to cast spells on you). Third, only one spell can be learned at a time, and it takes a long rest to learn them. If you've got one 'learned' spell waiting for a long rest, and you get hit with another, you have to decide whether to keep the old spell, or ditch it for the new one. Obvious rules patch is obvious, but that loophole needed to be closed.
As for the bit about the 'Soul' trait, I'm having a hard time deciphering exactly what your objection is. Constructs or undead with the 'soul' trait would be affected by Trap the Soul as an organic creature would. The purpose of this trait is to allow people to make construct or undead races without having to worry about the inability to resurrect one. It might clash with pathfinder lore, but the option is there for those who don't mind, or are making their own setting for their adventures.
Anyway, another couple traits. Spinnerets and Healing Secretions.
SpoilerShowSpinnerets (3 RP)
Benefit: This race is capable of producing limited quantities of natural silk. They can produce ½ pound per day without penalty, or 1 pound by doubling their dietary intake the day before. This silk can be sticky or not at the choice of the user. This silk has a value of 1 gold per pound, and can be used to make anything normally made from thread, cloth, or rope as well as webs. Silken items have one half the weight of cloth items but are otherwise the same as cloth items. Additionally, ½ pound of silk can be expended to cocoon a helpless, pinned, or unconscious creature of the same size or smaller. This is a standard action that provokes an attack of opportunity. You must make a successful grapple check to cocoon a creature you are pinning. The DC to escape a cocoon is 20 + your bonus to Craft: Silk. Craft: Silk is always a class skill for members of this race. (Note: If you want to be shooting sticky webs at foes to ensnare them, consider the trait Adhesive Secretions.)
Healing Secretions (3 RP)
Benefit: Members of this race are capable of naturally producing a medicinal substance that aids with healing, or who’s blood has medicinal properties. They are capable of producing 1 + con mod doses per day. If the medicinal substance is blood, the user cannot be at full HP. One dose can be applied to wounds to grant fast healing of 1 hp per round for a number of rounds equal to the user’s level. Alternatively, a dose can be applied topically to a patient to grant a +4 to any one heal check made by the user. This substance loses its medicinal properties after 1 hour after leaving the user’s body. Applying a dose of the medicinal substance is a standard round that provokes an attack of opportunity.
Your trait suggest they does not have souls which is contradicting the lore which says they have souls.