Can the Unchained detect the Fallen via Aetheric Resonance?
Page 184 of the Demon: The Descent book describes Aetheric Resonance as follows:
By expending a single point of Aether a demon can feel out Aether in the area around her for the remainder of the scene. Whenever a source of aetheric energy comes within the radius of her aetheric resonance, including a demon, she immediately becomes aware of the direction of the source and the quantity of Aether surrounding it.
Aetheric Resonance is based on Aether, which the Fallen do not have. In the last sentence of the description it mentions that powers that no not use Aether are not picked up by this ability. However, this is based on the concept of using Faith as-is. If you change the Fallen to be based on the God-Machine and therefore use Aether, they show up just fine (unless beholden to the same rules as an Unchained in Cover).
Can the Fallen detect the Unchained via Supernatural Awareness?
According to the Demon Translation Guide page 8-9 Supernatural Awareness works as follows:
Demons can sense supernatural energies at work in their vicinity, regardless of the source. This perception stretches a number of miles equal to the demon’s permanent Faith. The demon’s player rolls Wits + Composure as an instant action. [...] This doesn’t tell the demon the nature of the supernatural energy or its purpose.
This lets them detect any supernatural abilities being used within range, regardless of source. While the Fallen cannot detect who or what used the supernatural ability they can sense it happening. This is not limited to any power source, or even the use of Essence of any kind (Demon Translation Guide page 9): if there's supernatural powers at work, a perceptive Fallen can detect what's going on. Even if you change if the Fallen run on Faith or Primum, they still keep this ability.