Any time you have measurable concentrations of ammonia in your water, is a concern. Will it kill your fish? Most likely, No. NH3 is pH and temperature dependent and your test only shows, one time when you tested the water, there was some ammonia.

Dumping "thousands of pounds" of lime in your BOW unlocked previously unavailable phosphorous, leading to a bloom. It suggests your pond bottom is acidic. Just a guess...

While it is true aeration is not much help in controlling ammonia, maintaining DO levels while you have a boom and bust cycle of phyto/algae bloom, is definitely helpful.