Unfortunately, I think your change is not going to solve the problem without making more problems.
If you look at the failing tests, there are a number of cases where your change breaks existing scenarios.

One of the main reasons that TapRegion exists is so that we can bind widgets together into groups that don't trigger loss of focus. For instance, if you want to add formatting (bold, italic, etc.) buttons to a text field, but don't want clicking on those buttons to unfocus the text field, then you wrap them in a TextFieldTapRegion, which uses the same tap groupId as all of the text fields do, which is just the EditableText Type object itself.

Hope is not lost, though: To fix the problem you have, you'll need to figure out a way to give each text field a separate tap region groupId object that doesn't break the existing use cases. Perhaps a parameter on TextField that lets you supply the groupId object to EditableText, which overrides the default of EditableText?

@gspencergoog Thank you for your reply, your suggestions are great!