Watch Your Language: Detecting Multi-Lingual Language-Confusion Phishing

Detects phishing messages that deliberately mix writing systems/scripts/homoglyphs in the Subject line as ONE corroborating signal within a broader, multi-signal phishing pattern. Hardened against false positives: brand/product tokens (e.g. Microsoft, PayPal) are stripped before the Latin-script check so a lone brand mention in non-Latin correspondence doesn't count as mixed-script; the suspicious-URL signal requires a high-confidence credential/urgency term (not generic business vocabulary); sender risk requires the domain to be new to both the recipient and the organization; and at least three independent signal categories (not two) must corroborate the language-confusion signal before the rule fires.