Although both .bwt and .b6i files come from Blindwrite, it doesn't seem like bwt to b6i conversion is possible. This is due the fact that .bwt file is one of the auxiliary files for actual Blindwrite disk image (.b6i), so it's not something that you can convert or somehow export. But of course if you need something specific with these file types, it might be best to contact Blinwrite support or to reach out the online community.
Updated: July 24, 2023