This is my feedback based on the experience I've had.
Was attempting to fuse my Freya. So i happened to have 2 of the same 3* characters.
While in the training screen. I was not able to identify which of the characters I had. One had a more decent faith and I wanted to keep it. However, a long press on the character in that screen did not result in a "quick view" of the character. Not sure if this is intended but I had to move back into the base Hero screen in order to view. So it was rather dangerous, could have potentially fused the one with the faith I wanted. ]
Hope to have a future update where this is addressed so we can train knowing the characters we fuse are indeed the right one.
Thanks!