Overall that's not too bad. But the 2" of water after 12 hr might be. We don't know how wet or dry the ground was when you did the test; nor if your yard tend to flood or hold water when it rains.
So an easy and safe answer is to build a slightly raised bed. Take a close look at how
HMelendez did his bed for each nana plant. The tops of these corms appear to be about 6 to 10" above the ground.
An Update Of My Latest Nana Plants 2018!