This task is a follow up for T196051: CX2: Show reset option in the MT card only when the paragraph has been modified. Two known issues mentioned in https://gerrit.wikimedia.org/r/478584
Known issue 1: for some sections the "Reset translation" option does not get hidden after used. This is because the translation tracker thinks there are changes. That is a bug that should be fixed separately. There seems to be a race condition there where the isModified flaps between true and false because getUserTranslation flaps between the previously modified value and fresh value. When in debugger mode it flaps twice, but last result is correct.
Known issue 2: sections that contain references (or other complex tags) are always shown as modified if temporarily switched to another engine and then back. This is because the HTML changes slightly at some point and no longer matches. Some attributes get reordered and some escaping of quotes is different.