Elementor Custom fonts via functions.php

/**
 * Add Font Group
 */
add_filter( 'elementor/fonts/groups', function( $font_groups ) {
	$font_groups['rb_custom_fonts'] = __( 'RB Custom Fonts' );
	return $font_groups;
} );

/**
 * Add Group Fonts
 */
add_filter( 'elementor/fonts/additional_fonts', function( $additional_fonts ) {
	// Key/value
	//Font name/font group
	$additional_fonts['CustomFontName1'] = 'rb_custom_fonts';
	$additional_fonts['CustomFontName2'] = 'rb_custom_fonts';
	return $additional_fonts;
} );