Hello,
I hope you are having a very good day, also we love what you have done with the theme

To solve your issue please add following custom css to
Dashboard -> Appearance -> Customize -> Theme Options -> Advanced Options.

.gallery-caption {
  overflow: hidden;
    overflow-y: scroll;
    height: 100%;
}

This will provide a scroll on the long caption, allowing to scroll through the caption and read it all.

Best regards and Good Luck.