At around line 161, replace:
$sql = "SELECT`post_name` FROM {$wpdb->prefix}posts
WHERE `post_parent` = {$bp->groups->current_group->extras['gpage_id']} AND `post_type` = '{$this->page_slug}'
ORDER BY `menu_order` ASC
LIMIT 1";
$bp->action_variables[0] = $wpdb->get_var($wpdb->prepare($sql));

with:
$sql = "SELECT`post_name` FROM {$wpdb->prefix}posts
WHERE `post_parent` = %d AND `post_type` = '%s'
ORDER BY `menu_order` ASC
LIMIT 1";
$bp->action_variables[0] = $wpdb->get_var($wpdb->prepare($sql, $bp->groups->current_group->extras['gpage_id'], $this->page_slug));

And around line 188, replace:
$sql  = "SELECT * FROM {$wpdb->prefix}posts WHERE`post_name`= '{$bp->action_variables[0]}' and`post_type`= '{$this->page_slug}' and`post_parent` = $gpage_id";
$page = $wpdb->get_row($wpdb->prepare($sql));

with:
$sql  = "SELECT * FROM {$wpdb->prefix}posts WHERE`post_name`= '%s' and`post_type`= '%s' and`post_parent` = %d";
$page = $wpdb->get_row($wpdb->prepare($sql, $bp->action_variables[0], $this->page_slug, $gpage_id));