I am pretty sure that ONLY Bitfinex has standing in regards to claims of ownership of those coins. As a prior holder of those coins, you could still sue, but your suit may well get thrown out for lack of standing and/or timeliness, since recall that in about August 2016 when those coins were initially "hacked," Bitfinex created various kinds of socialize the loss tokens and also equity in the lost coins tokens. 

The socialize the loss tokes resolved themselves by around April 1, 2017 when Bitfinex bought out whatever were remaining of those tokens around that time.  There are likely some of the holders of the equity tokens that want to get their equity payout, but there claim would be against Bitfinex to make all good efforts to recover those coins.. whatever is remaining around 94k BTC remaining out of the 119 bitcoin that were hacked in August 2016.

I am surprised (but maybe not so surprised) that the US Govt has been able to hang onto those 94k BTC for so long without giving them back to Bitfinex, yet nation states engage in all kinds of injustices, and I doubt that Bitfinex and the US Govt are exactly on buddy buddy terms.

I had some BTC on Bitfinex at the time of the August 2016 hack, and I received that 36% socialize of loss payout, which was a bit of a rip off because of the way that the socialize the loss tokens were priced in the dollar value at the time of the hack and so then those tokens almost immediately reduced in value by 50%-ish because they were allowed to trade, and even though Bitfinex bought out all of the remaining socialize the loss tokens at 100% on about April 1, 2017, the BTC price had shot up during that time so there was some opportunity loss in value in regards to those socialize the loss tokens, but overall on a personal level, I still did somewhat Ok. in that situation since I did not sell my socialize the loss tokens at less than 20% their value as a lot of people seemed to be doing with those (even though I did sell some of mine at a reduced cost, not too many). 

I did not buy any of the Equities token, and I am thinking that they did not even allow USA citizens to buy those equities tokens.