Speaking as someone who’s played 5+ strings since the mid 90s, the vast majority of guitarists I’ve run into have no idea what your fifth string is. Just saying “B” wasn’t enough as they’d usually try to relate it to their own instrument and think it was a B above your G string. It’s almost comical how it still happens after all these years and with how mainstream 5-strings have become.
This. I've played with a few guitarists like this.