'Fade in' effect for Galv's Message Busts

I'm using Galv's Message busts, which can be found here.

The script has a slide effect that when the portrait appears, it slides the portrait onto the screen.
I was wondering if there is a way to include an effect where the busts simply fades in and out.
Disabling the slide effect allows the busts to fade in and out. But the problem is, the speed of the fading transition goes by too fast. The busts shows up and disappears instantly, making the text message look clunky.

Also(not really sure how to word this out perfectly but), I don't want the 'fade in and out' effect to occur if a text message shows a bust from the same face-set.

Please let me know if you have any additional questions as I'm not the best at describing things.