How does one understand the systems he/she creates?

So there's this hobby called language construction, and it's about constructing a human tongue from first principles. And there's a common problem encountered by conlangers (=people who participate in language construction): it is much easier to design the language & lexicon than it is to become fluent in it. Furthermore, because there are no other speakers, there's also no way to correct errors you are making. You're relying on your own mental model of the design you created, which is based on your intuition of your own system, and how are you going to correct your own intuition? It's like correcting an answer to a math problem: walking through the steps again isn't going to help you, because your flawed intuition is going to repeat the same misstep. Or like getting lost in a forest: whenever you try to walk your way out of the forest, no matter how straight you try to walk, there's a slight curvature to your walk causing you to go around in circles. You need a magnetic compass--something external to guide you in a straight line--to guide you out of the forest.

It's a bit easier to design software systems because there's a compiler and unit testing, both working together to yell at you whenever your intuition causes you to misstep.