Translate custom Menu from Functions

Hello,
First thank you for your plugin and help.

I have a SIGN IN, SIGN OUT and another page link IN MY MENU, THESE HAS BEEN ADDED FROM THE functions.php file and ofcourse i can’t see it in the wp-admin menus
So i can’t translate it from there

Is there any way to translate it from the fonctions.php file to switch between the 2 languages?

Here below the code in the functions file and the changes i have done:

function add_login_logout_register_menu( $items, $args ) {
 if ( $args->theme_location != 'primary' ) {
 return $items;
 }
 
 if ( is_user_logged_in() ) {
 $items .= '<li><a href="' . get_page_link('25026') . '">' . __( 'Spin Dashboard' ) . '</a></li>';
 $items .= '<li><a href="' . get_page_link('37') . '">' . __( 'My Account' ) . '</a></li>';
 $items .= '<li><a href="' . get_page_link('24842') . '">' . __( 'Sign Out' ) . '</a></li>';
 } else {
 $items .= '<li><a href="' .  get_page_link('37').'">' . __( 'Sign In' ) . '</a></li>';
  
   }

CHANGES I DID:

if ( is_user_logged_in() ) {
 $items .= '<li><a href="' . pll_get_post('25026') . '">' . pll__( 'Spin Dashboard','thegem' ) . '</a></li>';
 $items .= '<li><a href="' . pll_get_post('37') . '">' . pll__( 'My Account','thegem' ) . '</a></li>';
 $items .= '<li><a href="' . pll_get_post('24842') . '">' . pll__( 'Sign Out','thegem' ) . '</a></li>';
 } else {
 $items .= '<li><a href="' .  pll_get_post('37').'">' . pll__( 'Sign In','thegem' ) . '</a></li>';
   }  

But links are broken Now on my web page

I’m not a programer so please any advice about how to manage this? is it correct to keep the page ID as i did (ex: pll_get_post(’37’) or do i have to put something else

I can’t see Sign In, Sign out etc… in Strings translation in wp-admin
I can’t see them in Loco Translate

Wordpress: 4.9.4
Polylang: 2.3.4
Loco Translate: 2.1.3
PHP: 7
Theme: thegem

Thank you in advance