While I was creating my first big WIG-project I experienced something similar, how easy it is in some cases to cheat. And there will always be these, who will do it. Best example ist the "Reverse Cache Solver": you can get the answer to all of the -Waldmeister- based Wherigo reverse caches from different tool- pages/apps without even installing a WIG-Player on your device (that's why many cachers have trouble to play a Wherigo for real, 'cause the assume WIG is "three numbers to get the coords").
And you (as developer of a cartridge) can't fully control who's taking a shortcut.
I do check my cartridges with a crumbler before publish, if there are informations so obvious provided, that everyone can find it. e.g. the coords. For my play anywhere cartridge I do offer the location for the container, when the task of the cartridge is completed. But I try to avoid that the coords could be found in the plain text file just by searching for "N50" or "N 5 0"... this is no guarantee, but that keeps a few opportunists and their "Quick find T4TCA$H" (and then a mile long standard signature with tons of emojis, just to keep the "diamond author badge"-state in project GC up) logs away - it's always those. Sometimes I do add fake messages just for the lulz (and even once I hang a wooden "cheater" sign at one of these wrong spots).
The other thing is: create a cartridge on one hand and give players a task that only could be fulfilled outside of the cartridge where the answer is not in the cartridge at all.
For example: If you want a player to visit the last stage, give them an extra task there: "There's a sign with 2 words. Send an email to word1word2@example.com." Create an auto reply for this mailbox with the coords of the final location or give them just the latitude in the cartridge and the longitude via the mail (reviewer approved).
If someone uses a crumbler, at least they have to visit the lasts stage before the final. Of course you can add up different tasks this way - but be aware, that too many extra tasks will not be accepted. Maybe it fit's somehow in your story to have to send an email at the end ..?
In my opinion - if the cartridge sounds fun and doable in the cache listing - it will be played by those who appreciate a good WIG.