I would like to inform about a problem with other language characters in the titles (Cyrillic). The problem brakes the initialization of the Rehabtabs.
I have replaced:
$tab_id = sanitize_title( $tab['title'] ) . $key;
// No unexpected characters
$tab_id = /*sanitize_title( $tab['title'] )*/ 'rhbt_' . $key;
..which enabled proper work of the plugin. With urlencode/decode, the tabs were working, but were not connected to the correspoiding div.