I'm another one with this problem.
Everything was fine before iOS 11; now it's up the proverbial.
I've tried deleting and re-installing Word for iPad, and deleting and re-installing the font profiles. They work fine in apps such as Airmail.
They don't work in Word.
They do work in other Office-compatible apps.
I've tried SmartOffice — doesn't render them correctly, but does identify the fonts correctly, and simply substitutes them.
Ditto with Docs to Go.
Ditto with Apple's Pages.
Ditto with Google Docs.
Displays properly in Dropbox on iOS.
Displays properly in Documents by Readdle.
The common theme in all this is that user fonts will either work, or at least be substituted, in any and all iOS apps.
Except Word for iOS. Since iOS 11 rolled out.
What does that tell you Microsoft?
You need to fix it.