I'm creating an extremely difficult challenge that requires the use of advanced regex techniques. This challenge mixes multiple formats including complex email addresses with subdomains and special characters, international phone numbers with varied patterns (parentheses, spaces, and alternate international prefixes), dates with different separators (hyphen, slash, dot) in both YYYY-MM-DD and DD/MM/YYYY forms, and custom identifiers with multiple groups separated by hyphens. Additionally, I've i... (truncated)