We got a (reasonably) neat solution to avoiding an interactive prompt in an unattended BTM file (for instance when run from Task Scheduler):
KEYSTACK Y enter
copy sftp://somewhere.com/somepath/somefile.txt mydestination
INPUT /c /W0
The Keystack puts the Y response into the buffer just in case the copy command is to a new site, and it pops up the 'fingerprint - do you want to continue' message.
That means that the copy command continues regardless
The Input then flushes the Y out of the buffer (/c) if the prompt did NOT appear, or waits 0 seconds for new input if the 'Y' was used up and there is nothing to clear.
However, it would be nice if TCC was able to detect that it was not running intereactively (ie from a service or scheduled task), and NOT put out a prompt that will never get acknowledged. (We are using TCC20 - this may already be fixed in a newer version, but I have no idea).