Why would anyone rebuild Lal, specifically? She was important to Data. Data is gone. There's no emotional reason to bring back Lal.
In terms of technology - remember, we are talking about an android whose positronic brain was unstable and catastrophically failed. Not a sound technological basis on which to build something. If you really wanted to bring back an android, you'd resurrect Data in B-4s body, and not have to stretch much credulity to do it. B-4 was simple, but at least stable.
very possibleOr simply another Borg freed from The Collective, with no specific connection except to the former Locutus.