Have regulators every issued violations for cross-product contamination?
Yes. While not mentioning the terms "ADE" or "PDE" directly, the FDA and MHRA (Medicines and Healthcare Product Regulatory Agency) have both issued numerous warning letters or notices of violation to companies for failing to prevent cross-product contamination between "potent" and "non-potent" products.
Here are links to several specific cases:
MHRA Cites Pharmaceutics International for GMP Issues at Two US Sites