I wonder if there is a way to add CSS to the image model popup to make it behave as an overlay on hover?
Hi. Yes, it is possible to do through CSS. But so that it was a beautiful name must be placed inside the image, since the overlay layer applies to both.

Add "modal-overlay" class name to the addon CSS Class field. And use following code (add it to the costom.css file):
.modal-overlay .sppb-modal-selector {
position: relative;
}
.modal-overlay .sppb-modal-selector::before {
content: '';
position: absolute;
left: 0;
top: 0;
width: 100%;
height: 100%;
background-color: rgba(234, 163, 27, 0.6);
z-index: 2;
opacity: 0;
transition: opacity .3s;
}
.modal-overlay .sppb-modal-selector .text {
position: absolute;
left: 15px;
bottom: 15px;
}
.modal-overlay .sppb-modal-selector:hover::before {
opacity: 1;
}
Will looks like this

After all, you should pick up a different font color.