How can I extract or parse data from post contents’ shortcodes into an array?

Not really a WordPress question, but you can use the PHP function preg_match_all to extract all the text wrapped in [cs_text] tags like so:

function wpse_265295_extract_cs_text( $subject ) {
  $pattern = "#\[cs_text\](.*?)\[/cs_text\]#s";
  preg_match_all( $pattern, $subject, $matches );
  return isset( $matches[1] ) ? $matches[1] : [];
}

If you’re looking to extract arbitrary shortcodes:

if( ! function_exists( 'extract_shortcodes' ) ) :
function extract_shortcodes( $subject, $shortcode ) {
  $pattern = "#\[$shortcode\](.*?)\[/$shortcode\]#s";
  preg_match_all( $pattern, $subject, $matches );
  return isset( $matches[1] ) ? $matches[1] : [];
}
endif;