I am not sure if cryptocurrency inflow can stand for proof of funds documents for KYC verification i am sure using your traditional commercial banks statement of account is the most needed and easiest way to go through with such verification, in the few time that I pass through a KYC verification that need me to submit any source of funds I used my bank statement and it did work fine and the KYC was processed for me in no time, I haven't come across any cryptocurrency casinos that demands for me to submit my statement for documentation.

I have gone the highest in kyc when I was asked for my address which I used my utility to verify it that time, but no cryptocurrency casinos ask me to ever submit my banks detail, or being asked to provide any financial statements, although if you don't mind can you mentioned the name of the casino that demanded you to provide your statement of accounts