Welcome back Brion!
Heh, if it's so easy to regrow every part of the body then it gives a nice feature to abuse main character in future who may loose some limbs again since everything may be fixed...
Also May's missing finger too will regrow?
She will loose her love reminder
Well, since her missing finger is(Was?) on the right side, it's already gone(though the digestive tract, or what's left of it, of bloody mary) and since they are re-growing the arm by mirroring the uninjured left side, unless she speaks up, she'll most likely have her finger back.
Unless the finger missing is on her left side, in which case, she might end up with TWO missing fingers.
Also, we won't have to remind brion about the missing arm, which is generally meant to be missing, but sometimes isn't.