It's been "weeks", but that's still pretty quick to regrow a full-length tail, I'd say.
That's the wonders of nanotech, I guess! Ardent's nanobots have probably been working overtime to turn every bit of excess nutrient he consumes into a new tail. He's probably been 'overeating' by baseline human standards but something tells me that Alice knows how the technology well enough not to mind.
Notice that Gavia is flying and telekinetically manipulating the pail. I think that she has decided that she
is not going to touch the dirt (yuck!) or get her hands dirty with these 'primitive' chores and implements (yuck!). I have the feeling that Ardent is going to throw himself into the local culture feet first (if he and Jack don't end up as BFFs, I'll be surprised). I'm also betting he'll unintentionally cause a lot of trouble along the way! Gavia, on the other hand, will probably have to be dragged kicking and screaming into socialising with the 'primitives' or having
anything beyond the bare minimum to do with this world where she's stuck for the moment. Whilst Ardent is happily wearing what I suspect is a shirt Jack leant to him, Gavia is still wearing her futuristic space-robes. Wearing the disgusting bio-product apparel of the Preserve is another thing that she will only do under threat of immediate harm.
Something tells me that Alice would consider dragging Gavia kicking and screaming to do something or forcing to do something to fit in a personal pleasure. I'm waiting for the first time we see poor Gavia stuffed into one of those 19th Century dresses to attend the Town Fayre or something.