I won`t pretend to understand all the science of it, but high ammonia rates really mess with the ammonia munchers.
Oh, some of the ammonia will still get to be nitrate, just not all of it, and it seems to stay that way for an awful long time.
You end up with a tank that has both, high levels of ammonia and nitrates.
Swell, a tank full of highly toxic to fish problems.
Used to be, when doing a fishless cycle you would be told to get your ammonia level up to the 5ppm range.
So many had problems with their cycle getting “stalled” that some started using a lower ammonia dosage and it worked way better.
Now, those who know, start their cycle with a 2-3ppm level and have no problems.
Even those that swear by the “bottle cycle” products can have a hard time of it with high ammonia levels.
As much trouble as you can get into doing a fishless cycle, when you try to do it with fish, it often doesn`t end well.
All the OP can do is WC to help save the fish.
Since MOM is doing the feeding, you might try to get her to feed every 3 days, or even once a week, until your tanks chemistry gets back on track.
Might be a tough sell, trying to convince her that the fish are not “starving to death”, but would really help your tank.
Other option, pull the fish and start over.
Good luck.