You can add this code to your theme’s style.css file to override default LatePoint font family, replace YOUR_FONT_FAMILY with the font family you want to use:

.latepoint-w { font-family: YOUR_FONT_FAMILY!important; }
.latepoint-lightbox-v2 h1, 
.latepoint-lightbox-v2 h2, 
.latepoint-lightbox-v2 h3, 
.latepoint-lightbox-v2 h4, 
.latepoint-lightbox-v2 h5, 
.latepoint-lightbox-v2 h6 { font-family: YOUR_FONT_FAMILY!important; }