Is possible to use function in is_page array?

Hi, I have small troubles today :).

I need simple WP website in three languages (don’t ask me why I don’t want to use a language plugin) so I decided to create simple functions in functions.php:

function jazyk($jazyk) {
	if($jazyk=='en') { return 'Greek cummunity Brno'; }
	elseif($jazyk=='gr') { return 'ΕΛΛΗΝΙΚΗ ΚΟΙΝΟΤΗΤΑ ΜΠΡΝΟ'; }
	else { return 'Řecká obec Brno'; };
	}

function jazykid($jazykid) {
	if($jazykid=='en') { return '12,13,14,15,16,17,18,19,20'; }
	elseif($jazykid=='gr') { return '21,22,23,24,25,26,27,28,29'; }
	else { return '3,4,5,6,7,8,9,10,11'; };
	}

and then I call these functions from header.php:

if(is_page(array(jazykid('en')))) { echo jazyk('en'); } elseif(is_page(array(jazykid('gr')))) { echo jazyk('gr'); } else { echo jazyk(''); };

But it doesn’t work, when I use this:

if(is_page(array(12,13,14,15,16,17,18,19,20))) { echo jazyk('en'); }

it works fine.

So my question is… is there any way how to use functions inside the array? Or how to create a global variable and use it instead of typing IDs manually again and again?

Thanks a lot guys, Machi