User blog comment:Linathan/Unit Spotlight: Courageous Heart Alma/@comment-68.98.29.49-20150325061327

I'm trying to find the video where Ushi mentioned it, but someone tested it and BC gain per turn by such leader skills/buff caps at 10 bc per turn. So a Alma lead (5 bc per turn) with Grahden's 6 star SBB buff (6 bc per turn) would only give 10 bc per turn instead of 11.

Not sure if this only applies to Japan version or still does though.