Hi everyone,
Adding columns using Column order, etc., is problematic when adding large numbers of columns because the Add button moves down.
By placing the Add button in such a way that it is slightly hidden in the window frame, columns can be added continuously. 
Thanks @takuya_miyai for this tip !
It may be an opportunity to make a “feature idea” post ? At seeing your post, I realize that’s something that might be improved in the editor UX.
Hi @Aurelien
Yes, it’s really a problem that I would like to see solved by improving the UX of the AppSheet Editor.
Even if it is improved, I think it will take time, so I hope these tips will help everyone.