In English, think of all the plurals for which no ‘rule of grammar’ exists; you just have to memorize them.
Moose -> moose
Goose -> geese
House -> houses
Mouse -> mice
Etc.
In English, the exceptions to the rules are arbitrary and numerous. English is also a moving target. From a logic problem perspective, English grammar is more of a practical brute force endeavor than an interesting one. When I read the article, I was wasn’t comparing the problem to English grammar, but rather comparing it to a logic puzzle that has a perfect solution.
Could not resist Gad Elmaleh's frustrations about learning English (he did very well to do an hour's standup in English):