Unless we get confirmation the Dashing Swordsman advances spellcasting I wouldn't use the possibility to discount advancement in Bard, because that risks a slippery slope where unstated homebrew can explain every deviation. We already have previous evidence of Elan choosing to continue his Bard levels rather than only Dashing Swordsman, so I think that's reasonable to peg as Bard 16 unless other evidence emerges.