BTF format is typically used for scanned documents/pictures captured by Brother devices and as such it may not be possible to create them using other means or convert other files to this format. Hence a jpg to btf conversion seems to be highly unlikely.
This conversion entry was verified by us and conversion was flagged as wrong or not possible.
Usually this happens when the conversion would try to convert different types of data between each other, such as audio to image, or it is not possible because incompatibility between programs, caused by closed file formats, very limited support etc.
If you find entry that you feel is flagged as bad wrongly, please tell us in the discussion below with as much as information as possible so we can fix it.