If you accidentally taste soap then nothing bad will happen other than you may have an upset stomach and a bad taste in your mouth for a few hours.
If you do taste soap or get soap in your mouth then simply spit it out and wash your mouth out with some water and then some mouthwash.
You may need to use some mouthwash a few times through the day or more to fully get rid of the soap taste in your mouth.
You will not get fully sick from soap even if you ingested a bit of it.
I was actually forced to keep some soap in my mouth when I would cuss and my dad always put a bar of soap in my mouth and made me keep it in my mouth for at least 2 to 5 minutes.
Then I could wash my mouth out with water and mouthwash.
I only got an upset stomach and vomited a few times but I was okay after that,.