I like to think the two of them are not fused, and that the one on what looks like Opassa beach is Kid while the one in our dimension's Tokyo is the "true Schala". They do both seem to have gained a few traits from each other, namely Kid's choice of clothing and Schala's now permanently blonde hair. But they are clearly shown in two locations in space/time in the same ending so that's my conclusion. Remember the Chrono stuff doesn't take place in our dimension, so for Schala to be able to get "here" so to speak, she would need to be powerful one way or another. Absorbing energy from the Time Devourer makes a lot of sense.