When BB pools are imported directly into moodle (BB 6+ option) the true/false questions all come in as true. I've seen this in earlier versions (1.5.4) but neglected to put in a bug report.
I've attached a BB export zip file to play with.
If decompressed, you can view the dat file, and the "varequal47" field seems to show the correct answer- though i'm fairly new to this parsing of files.
Currently seeking programatic workarounds, as we have some critical conversions to do. Basically, when doing conversions across an institution, it's all or nothing. If 10% of your questions throughout your pools dont convert, it's back to manual for the whole thing. That's the only reason i put it as major - even though true-false is usually less than half of test pools.