By late 2021, the community emphasized that a "verified" build must account for file integrity. Always verify the SHA-256 checksums of your ISO files before moving them to your multiboot HDD. A single corrupted byte in a 5GB Windows ISO can lead to mysterious installation failures that are difficult to diagnose.
Recommendation: Only for advanced users who need legacy boot tools and can verify/update components manually. For most people, a newer tool like Ventoy + your own curated ISOs is safer and easier. multiboot hdd 2021 final verified