Rowan made sure his forging plans were perfect, rechecking them again and again even when he knew everything was up to standards. It was not because he was nervous, he was only looking out for unexpected events, one could never be careful enough.
His mental space would not be able to hold the portion of his consciousness but a Natal Treasure should be able to do so, and what was impressive about Natal Treasures was that you could gain multiple Natal Treasures at higher ranks, but you could only have one mental space, this granted Explorers a great advantage over most creatures in Reality outside Doom Star.
At the Glorious Rank, he would only be getting one Natal Treasure, and at the Legend Rank, he would be getting three Natal Treasure, although Rowan had a separate plan in mind.