It seems like this issue isn’t to do with the Corvid language so much as Wix’s data structure.
BTW, if you ever need to do this again for whatever reason…it is much easier to export your database as a CSV, open it up in an IDE like Visual Studio or Codium, and use the ctrl + f tool to delete all your old fields at once.
Then all you have to do is import the new data into your new database. It’s much easier than it sounds and should take like 10 minutes.