Toucan (188.8.131.52) is consistently creating a tmp file inside it's own folder. This happens when I create a 7z archive from the backup tab. I haven't tested this with zip, but I assume it's just as susceptible.
I believe the tmp file should be created on the backup's target. First, the target is more likely to have more capacity than the backup's source. Second, it would help eliminate the undesirable scenario where Toucan happens to resides on the same backup source from which the tmp file is being written to. Thirdly, it just feels right.
In summary, it would be nice if the tmp file just followed the destination like 7-Zip does.
Hope my suggestion helps. Thanks for the great program!