Impossible to say.
My point is simply that i would newer use tank that was used and then left to sit for years dry, before i dissasemble, clean and then reseal everything again.
Leak, no leak, theres no way to know how old is silicone in joints, or how much he degraded over time....
Leaking is easy fix, structural integrity of tank is something totaly different...
Yes, it maybe holds water for now, question really isnt will it hold water, but for how long it will hold it....
This is one afternoon job, slice it apart, clean and wash glass, put it together and let it dry few days..... Fill it, test for leaks and done.....
I'm not professional tank builder, or anything, but i buildt many tanks over the years, not a once i had leaks, or any problems.....
Clean glass, quality silicone, little time and patience is all u need to be safe long term.....
That is my opinion, i would newer trust used tank and simply put water in it...