How to bring custom block theme suggestions into the right hierachy?
What you need is simple array manipulation. Basically split of the original suggestions add the the suggestions and merge the suggestions again.

Some like this should work (untested).

function oeb_theme_suggestions_block_alter(array &amp;$suggestions, array $variables) {
  ...
  $first_sugestions = array_slice($suggestions, 0, 2); 
  $last_sugestions = array_slice($suggestions, 0, 2);
  $first_sugestions[] = 'block__' . $blockType . '__' . $bundle;
  $suggestion = array_merge($first_suggestions, $last_suggestions);
}