However, people can at most proof that they did deposit some CFC to ShareX. It is more than unlikely they can show proof they didn't sell their ShareX holdings and then withdraw BTC afterward
Not that hard to track via the blockchain explorer, I'm confident I could track this.
Harder to prove any bought on the exchange but not appearing in ur online exchange wallet address.
In my case I'll be just claiming those I sent to the exchange for the swap (luckily for staking purpose most the times earlier I bought I'd sent back to my wallet), any bought on the exchange that I can't now prove I'll just write off as lost (none of which is in anyway coffeecoin's fault) along with the various other coins I lost in sharex including some btc

Nope. I do daily trades on exchanges and I'm sure blockchain explorer cannot track this
The problem is that if people did sell their CFC holdings on ShareX, blockchain explorer still showed no change of their balance as long as the new buyer did not withdraw
No offense but it's how blockchain explorer works. Nothing can be tracked if no new transaction on the network
That means our dev can only know these coins are still on ShareX, but he cannot know who is the owner of the coins
probably the only possibility is to keep all coins of sharex in an account. Then let everyone request its coins with an transaction id or a trading claim. If noone is complaining, everything is alright. If someone is complaining you probably have to solve that somehow in a "human" way without a technical help.
I mean, they can be glad, if they are getting their coins back already. Hopefully there are no greedies ;-)