Having a Sigil app that allows editing would be awesome but not very feasible. The way I’ve found is to use the app/reader’s ability to make highlights/annotations. Depending on the reader’s capabilities you can either transfer/sync the annotations file to your computer, or just sequence through them on your reader while you fix it in Sigil.
I don’t know of any automated method… that would take a fairly advanced program to deduce the error from the annotation.
You’ll need to find a reader/app that has those abilities. The one I use is no longer available on Apple’s store
