with the cdb file positioned on iCloud and correctly opened, after importing transactions I received this message:
I run latest Catalina, latest iCompta on MBP 2015The operation couldn’t be completed. (GSLibraryErrorDomain error 6 - clonefile(/Users/silvano/Library/Mobile Documents/com~apple~CloudDocs/Drive Files/iCompta IMPORT/bank input overwrite/icompta db.cdb, /Users/silvano/Library/Containers/com.lyricapps.iCompta6/Data/Library/Autosave Information/EA84EC66-E782-4ABA-B7AF-A496B3F58ACC.genstore.noindex/.genstore_staging/GP79ZqE/7D0CBB34-A1D4-4C5B-9A3E-F195AD4CC2CF.cdb) failed)
force quitting compta and reopening and doing everything from scratch caused the issue to disappear.