Support Polish characters.

See https://kriesi.at/support/topic/custom-font-with-cyrillic-symbols – you can add a new font or overwrite an existing font – a list of all supported fonts can be found in wp-contentthemesenfoldincludesadminregister-admin-options.php

'Alice'=>'Alice',

'Allerta'=>'Allerta',

'Arvo'=>'Arvo',

'Antic'=>'Antic',



'Bangers'=>'Bangers',

'Bitter'=>'Bitter',



'Cabin'=>'Cabin',

'Cardo'=>'Cardo',

'Carme'=>'Carme',

'Coda'=>'Coda',

'Coustard'=>'Coustard',

'Gruppo'=>'Gruppo',



'Damion'=>'Damion',

'Dancing Script'=>'Dancing Script',

'Droid Sans'=>'Droid Sans',

'Droid Serif'=>'Droid Serif',



'EB Garamond'=>'EB Garamond',



'Fjord One'=>'Fjord One',



'Inconsolata'=>'Inconsolata',



'Josefin Sans' => 'Josefin Sans',

'Josefin Slab'=>'Josefin Slab',



'Kameron'=>'Kameron',

'Kreon'=>'Kreon',



'Lobster'=>'Lobster',

'League Script'=>'League Script',



'Mate SC'=>'Mate SC',

'Mako'=>'Mako',

'Merriweather'=>'Merriweather',

'Metrophobic'=>'Metrophobic',

'Molengo'=>'Molengo',

'Muli'=>'Muli',



'Nobile'=>'Nobile',

'News Cycle'=>'News Cycle',



'Open Sans'=>'Open Sans:400,600',

'Orbitron'=>'Orbitron',

'Oswald'=>'Oswald',



'Pacifico'=>'Pacifico',

'Poly'=>'Poly',

'Podkova'=>'Podkova',

'PT Sans'=>'PT Sans',



'Quattrocento'=>'Quattrocento',

'Questrial'=>'Questrial',

'Quicksand'=>'Quicksand',



'Raleway'=>'Raleway',



'Salsa'=>'Salsa',

'Sunshiney'=>'Sunshiney',

'Signika Negative'=>'Signika Negative',



'Tangerine'=>'Tangerine',

'Terminal Dosis'=>'Terminal Dosis',

'Tenor Sans'=>'Tenor Sans',



'Varela Round'=>'Varela Round',



'Yellowtail'=>'Yellowtail',

Eg if you want to use Open Sans with “Latin Extended subset” characters add following code to the bottom of functions.php:

add_filter( 'avf_google_heading_font',  'avia_add_heading_font');

function avia_add_heading_font($fonts)

{

$fonts['Open Sans'] = 'Open Sans:400,700,400italic,700italic&subset=latin,latin-ext';

return $fonts;

}



add_filter( 'avf_google_content_font',  'avia_add_content_font');

function avia_add_content_font($fonts)

{

$fonts['Open Sans'] = 'Open Sans:400,700,400italic,700italic&subset=latin,latin-ext';

return $fonts;

}

Note: Not all google fonts support all subsets. You can search for fonts which support “latin extended” characters here: http://www.google.com/fonts/