How to create a mermaid using Spheres of Power?

Spheres of Power and its related splatbooks recently came under the valid books my RPG group is allowed to use.

The system is quite something, and far different from anything I have ever used in Pathfinder. So far, I’m liking it quite a lot, and my group is having a blast building characters with those new options in mind.

One of the players wants to RP as a mage-like character that happens to be a mermaid. Her plan is to emulate this "mermaidness" not by picking a different race, but by using the feats Transformation and Hybrid Transformation. (Check this link for details on them.)

Transformation says:

Benefit: Choose one (transformation) Alteration sphere talent that does not cost a spell point. If you choose Anthropomorphic Transformation and are humanoid or of a similar body plan, choose one other (transformation) or (body) talent to use when choosing traits to be granted by Anthropomorphic Transformation.

As a full-round action, you may assume the form of a single creature whose type corresponds to this form talent per the shapeshift ability of the Alteration sphere as a supernatural ability.

The same creature (wolf, spider, treant, etc.) is mimicked and the appearance of that creature is retained each time. The chosen form may be the same as your base size or else Medium or Small, applying size change bonuses and penalties as appropriate if this is not your usual size. When assuming your chosen form, you gain the chosen size. This transformation lasts until you choose to revert to your original form as a full-round action.

You gain all the abilities granted by this form (movement modes, natural attacks, special abilities, etc.) but do not gain any traits from the Alteration sphere as part of this transformation. Treat your Hit Dice as your caster level for the purposes of this effect. This is a polymorph effect. Possessing this feat gives you the shapechanger subtype.

So, from reading this, transformation could be used to, for example, transform her mage into a fish, dolphin or similar creature if she picked "Aquan Transformation". She couldn’t transform into a mermaid, however, since the Aquan Transformation doesn’t have limbs besides a head and a tail by default.

Hybrid Transformation grants a few new options.

Benefit: When changing into a form granted by the Transformation feat, you may instead assume a hybrid form, blending your base form and your transformation form. This cannot be used if your transformation form is already similar to your base form, such as a humanoid using Anthropomorphic Transformation.

When in hybrid form, you gain all limbs, natural attacks, special abilities, and movement modes from your transformation form, but without changing your basic shape nor melding your equipment. You may choose to retain limbs and movement speeds from your base form if your transformation form lacks them or has lesser versions, such as a humanoid keeping arms when assuming a hybrid form based on Serpentine Transformation or Vermin Transformation, adding legs to Aquan Transformation, or a winged creature retaining its wings under Animalistic Transformation.

If your transformation would grant you additional legs, you may instead gain them as arms, although they do not grant any additional attacks, are not strong enough to gain any natural attacks, and may not assist in wielding weapons, activate magic items, or wield a shield. They may hold items and as a swift action you can use them to draw a sheathed or hidden weapon, don a shield, retrieve a stored item, load a crossbow, open a door, pick up an unattended item, sheathe or store an item, or take other non-offensive actions involving manipulating objects. Items do not automatically merge with the new form if it is capable of wearing them, but the size of the items does not change if they do not resize on their own.

From our reading from it, if one can add arms to a Vermin or Serpentine transformation, or legs to an Aquan Transformation, one can deduce that it is possible to put arms on an Aquan Transformation, thus emulating the desired mermaid form as many times and as long as she wants during the adventuring day.

However, since I’m extremely unfamiliar with spheres of power, I have no idea if I’m missing something.

Is this strategy legal? Is it possible to create a mermaid-like character by picking up those two feats?