Looking at your audiogram, it looks like you only have a mild mid frequencies loss in both your ears around 1 and 2 KHz, and although your right hearing loss continues to be mild to moderate at 3 and 4 KHz, your left hearing seems to be OK in these frequencies.
So I find it consistent with your description that the Transparency mode seems to work for you with your loss, but without enough ooomf. I would contend that the Transparency mode is still only providing flat amplification of the ambient sounds, but because it doesn’t provide the slight boost that you need in the 1-2 KHz range to compensate for your mild loss in that range, hence it’s lacking the ooomph like you said (compared to your hearing aids which do compensate properly for your loss in that range).
You do have a mild loss in the 3-4 KHz range on your right ear, but you don’t have that same loss in your left ear, so I would contend that even though the flat Transparency amplification also lacks the ooomph for your right ear between 3-4 KHz, it’s not as noticeable a lack compared to the 1-2 KHz, simply because your normal hearing in your left ear in the 3-4 KHz makes up for that mild loss in your right ear there.
So all in all, I think your perception of how the Transparency mode works for you OK, but not enough ooomph compared to your hearing aids, is still consistent with the AirProds Pro only giving you flat amplification and not aided/boosted amplification based on your audiogram.
The telltale sign would be that if you find streaming content from the iPhone giving you enough ooomph for your hearing loss, but the Transparency mode doesn’t give you enough of the same ooomph, then that confirms that your streaming content is aided by your audiogram, but the Transparency content of the ambient sounds is not aided the same way.