Bounds check the result of trap_R_BoneIndex. This function can fail with a result of -1.

See comment below about the abstraction. Barring a correction there (which would change this to store by value), this can also use std::unique_ptr instead of std::shared_ptr.

Do we really need this abstraction? Seems like a case of over engineering.

If the above is changed to .insert, this can be changed to just use the count parameter of the std::vector constructor to avoid an allocation.

prefer .insert with std::move()

Do we really need to load an animation for WP_NONE?

This returns "true" in all possible paths. This makes the return value essentially useless