English rules of thumb with grep

As a native spanish I was wondering about the words ending in tial or cial, in Spanish they end in cial, for example English tangential => tangencial versus English spacial => espacial

grep to the rescue:

grep -cE "[^aeiou]tial$" british-english => 40

grep -cE "tial$" british-english => 43,

conclusion: with 3 exceptions the rule is (no vowel) + tial

grep -Ec "[aeiou]cial$" british-english => 21

grep -Ec "cial$" british-english => 26, so with 5 exceptions (vowel)+cial.

There must be many low hanging fruit to collect rules of thumb using grep to help you use words correctly. Perhaps someone can give a hint about some of them.

Edit: It seems this rule is well known: https://howtospell.co.uk/cial-and-tial-spelling-rules