I think the Slow Resistance is a valueable stat even if it doesn't feel like it, I would avoid buffing that stat drastically.
As for the Ghosting effect I would rather have it be activated when channeling an ability or when using an ability and you are ghosted for X amount of seconds, because having a permanent Ghost effect on Swifties at it's current cost would be somewhat gamebreaking since so many mobile champions could abuse this effect...

I'm down for some buffs to Swifties but this approach needs to be taken with heavy consideration. Maybe even just increasing the Slow Resistance if you are channeling an ability or are continuously affected by a Slow which decreases it's effectiveness, which is capped at X% (but even then I would think that this increase should be somewhat minor).
I don't know, it just feels very risky to do any changes when Swifties aren't that bad just a little underrated in my opinion.