no, i hold that you could make a perfectly viable swordmage that satisfies the concept built entirely with existing mechanics, the components exist, the issue is just that they're scattered throughout several different classes
the issue with 'just refluffing' is the existing sub/classes never managed to get the swordmage thing right, if they did we wouldn't be asking for one, in all their attempts the issue is either that the two sides are imbalanced to one side or the other(5 blue and 1 yellow does not make proper green) or not synergised together well enough(alternating blue and yellow also doesn't make green), the eldritch knight is a conceptually good baseline but leans too hard on the martial side of things, 1/3rd caster just isn't enough, swords bard, bladepact and bladesinger on the other hand have too much caster design in them, BM maneuvres aren't counted as magical damage, and the paladin is taking it's gish thing in a slightly different direction, it's a good thing, but it's not the swordmage thing - feeling the concept is more than just fluff but that doesn't mean we need NEW mechanics, i admit there could probably be a few more spells to support the archetype too but i wouldn't consider those new mechanics so much as just more of an existing one.
just give us a foundation that's like, d8 arcane halfcaster, the rogue's weapon list, extra attack, the bladepact feature that lets you use your casting stat for attacks and damage with your chosen weapon, the EK feature that lets you sub out an attack for a cantrip-maybe even let the cantrip damage type bleed over to the weapon attack damage, let them use their weapon as an arcane focus and their weapon counts as magic damage like monk's unarmed if it's not already, a non-radiant smite would likely fit well but that'd probably infringe on paladin's style a little too much.