Slight inconsistency in forum topic and post counts

Hello,

I am attaching the following files, please note:

• In original_forum_post_count.png, it can be seen that the original phpBB forum reports 1400 topics and 42034 posts.
• In migration_results.jpg, one can see that 4 out of 2 (?) forums have been migrated, 1933/2088 private messages (known issue), 1404/1404 (?) topics with 1393 messages and 40667/40667 posts and 0/39 attachments (known issue, with media module enabled)
• In migrated_forum_post_count.png the migrated forum reports different numbers: 1392 topics, 42020 posts...

Is this variation in imported topic numbers and posts normal?

The import messages for the topics appear to be 1 special warning (see first warning below) and 1392 identical warnings (about the nid):

169	Informational	Undefined property: stdClass::$parent_id File C:\xampp\htdocs\drupaltest\sites\all\modules\phpbb2drupal\phpbb2drupal_core.inc, line 248(file: C:\xampp\htdocs\drupaltest\sites\all\modules\phpbb2drupal\phpbb2drupal_core.inc, line 248)
2037	Informational	Undefined property: stdClass::$nid File C:\xampp\htdocs\drupaltest\modules\forum\forum.module, line 333(file: C:\xampp\htdocs\drupaltest\modules\forum\forum.module, line 333)
2040	Informational	Undefined property: stdClass::$nid File C:\xampp\htdocs\drupaltest\modules\forum\forum.module, line 333(file: C:\xampp\htdocs\drupaltest\modules\forum\forum.module, line 333)
2043	Informational	Undefined property: stdClass::$nid File C:\xampp\htdocs\drupaltest\modules\forum\forum.module, line 333(file: C:\xampp\htdocs\drupaltest\modules\forum\forum.module, line 333)
2046	Informational	Undefined property: stdClass::$nid File C:\xampp\htdocs\drupaltest\modules\forum\forum.module, line 333(file: C:\xampp\htdocs\drupaltest\modules\forum\forum.module, line 333)
...