The Legality and Difficulties in Harvesting Compendium Data (Hypothetical)

[Wayside]

That would probably not be a copyright violation (if only used for personal use - it would likely fall into the category of "fair use"), but certainly could violate terms of use or other agreements. If strictly for personal use (only) not too big a deal. If used for any other purpose, it would at least be a violation of ToU and/or ToS and copyright laws and possibly a host of other things, too.

Using software in violation of its terms is basically always copyright infringement because of how computers work. See MDY Industries, LLC v. Blizzard Entertainment, Inc et al.