The creator and owner of BitGrail has been very irresponsible. He won't accept any responsibility and won't collaborate with the Nano team. It seems to me personally that he has been trying to cover up his insolvency for much longer than when he first announced it.
Other exchanges have been more helpful in actively trying to track the funds than BitGrail themselves. Thankfully though, Francesco has recently said that he has a "recovery plan". I don't know how how much you can take that though. Hard to trust him.
The fact that "Bomber" of Bitgrail blames some purported flaw in XRB's protocol is telling. Especially when Kucoin and Binance don't see any problems. Can't accuse him of stealing the XRB - yet. But it's reasonable to conclude that he was incompetent when it came to the exchange's funds. May or may not be criminal. But I'd say he's liable should there be a civil suit.