Please do not consider the ByT to be a primary source. There is much discussion about its provenance. (i have a copy beside me). The general view is that was "enhanced" as a vanity project in the late 18th century and should NOT be used as a primary source.
Unfortunately like many vanity projects the Gwentian Chronicle, as it is also known, has dedicated followers. However, as we know, dedicated followers do not necessarily let the truth get in the way.