Updated the original post. The old regular expression didn’t work since the editor ate a \ at the start and \[t] means something different than [t].
You can do this replacement in two steps without regular expressions:
- Replace all
= "with=<tab>". - Replace all
" --"with"<tab>--".
Then remove the lines at the start just like I mentioned above and it should work. (Does so for me in Excel.)