In Xanathar's Guide to Everything under the Bard College of Swords Blade Flourish feature (page 15) it says "Whenever you make an attack action...". Was this meant for strictly melee attacks or can Blade Flourish be used with ranged attacks?
Yes! Blade Flourish can be used with Ranged Attacks.
The text is very specific that it only requires a weapon attack (not a melee weapon attack or even an attack with a sword).
Additionally, Jeremy Crawford specifically states:
Blade Flourish intentionally requires a weapon attack—not necessarily an attack using a sword.
While you can use the sword flourish with ranged attacks, other features in the class (like Fighting Style) do not work with ranged attacks.
The name of an ability does not limit what the ability does
The text is:
Whenever you take the Attack action on your turn, your walking speed increases by 10 feet until the end of the turn, and if a weapon attack that you make as part of this action hits a creature, you can ...
A “weapon attack” can be a melee or ranged attack with a melee, ranged or improvised weapon.