What you need to do is to file a partial removal bug to ask the FTP Masters to remove bibletime from the architectures where it can no longer build because of its changed build depends.
There are examples at https://ftp-master.debian.org/removals.html Note that page includes full removals and partial removals. You only want to file a partial removal. You can make the package arch:any again. That way, the package will build on additional architectures automatically whenever qtwebengine-dev is built on any additional architectures. Thanks, Jeremy Bicha
