I felt the same way when I first saw Ord Pardron mentioned in the aforementioned map in the Imperial Handbook. That planet in particular has always stood out to me since I was first introduced to the EU by The Last Command (I read TTT in a weird order based on what happened to be available at garage sales). Even ignoring it, I'm over the moon that so many of those others Legends worlds with a long, rich history of supporting the Rebellion were recanonised. Sadly not. It's the sole exception, with every other planet placed on the map. The map itself and the planets listed on it are from an in-universe document which appears to be extremely early GCW. (The actual timeline placement is unclear. The chapters are in chronological order and the map appears in the first, which covers the earliest rebellion prior to Scarif, but we know from Lost Stars that D'Qar was only scouted by the Rebels post-Hoth). Mirrin goes unmentioned on the document itself, and is only referenced in the handwritten annotation by Ematt.