I guess the situation would be potentially more relatable if say...

I guess the situation would be potentially more relatable if say you had given you broker the instructions to buy shares, the money had transferred from your account, the broker said the shares had been bought, but they don’t show up in your trading account due to some processing situation. In that situation you’d likely argue that your were a shareholder, your broker would support you, but you’d have no registry entry to show that being the case … actually given we are talking about shares in a non-listed company, it likely still isn’t a reasonable equivalent. Note I’m not saying at all that Z has the shares or the rights to the shares - merely drawing attention to the lack of a registry entry of holding doesn’t preclude an argument that a person is entitled to being a “shareholder” - you’d want to see what evidence there was between say the buyer and the seller to know if a sale had happened.