There are definitely a few ways to approach this. If you want to keep it as is, just a message displayed when the hint button fails but detects 1 or more wildcards 'hint cannot use wildcards'
I don't know what sort and search method you are using for hints, but several methods come to mind to do a search that only use a fraction of the dictionary.
Also would love to talk Kickstarter/Steam/Publishing with you if you are interested in that route. You can find me on discord under the same name.