WER issue-round number set on O
Essentially, you're using someone else's IP for your own purposes. Add to that the fact that WER, it's interface, file formats, etc., are almost certainly covered under various copyrights, and you can probably come to the right conclusion. Granted, if you're not trying to profit, it might seem like it's “no harm, no foul” - but copyright lawyers rarely see it that way.
If you feel you have a utility that can make use of Wizards' IP for the benefit of all, then you might consider discussing a licensing arrangement with Wizards.
This post seems incomplete without the internet cliche, “IANAL”. :)
d:^D