what mean hot-wallet and cold-wallet?

-> does it mean the cold wallet are coins not used in trades the last hour?

Or are these thinks not connected to each other? What means not important to which time you trade or put your money (EUR or BTC) on the platform it is only covered by the cold-wallet.

In my case I have put coins to the platform at around 11 pm 11th of April traded at 4am and 8am and between 10-11:30am the platform trade locks like a control loop with to strong gains (12th of April).
All my stuff on the platform is in BTC.

As long I can understand everything, the delay of withdraw of EUR is that big that the money couldn't be lost but the delay of Bitcoin withdraws was only 30min in my case (Tested the day before). If the BTC is shown by the bitcoin network he could not bring them back. So the graphs lock like the problem started at 10am what means that 1h of loses of BTC is possible.

Please give me a good feeling and say that I'm wrong.