Both .ftb and .ftw files come from the genealogy software called Family Tree Maker and thus if any software would be capable of ftb to ftw conversion, it would be this one. Considering that .ftw files are projects, it is safe to assume that this is related to importing content to projects. But of course, if you need anything specific or have other issue, it would be best to contact Family Tree Maker support.
Updated: July 26, 2023