I have implemented this nice rule that suggests replacing “certo” with “exato”:
However, there are many false positives since there isn’t a good way of checking if the nouns are valid.
All I have done was to see the results and try to remove the most common incorrect ones.
See the before and after .txt in the GitHub commit.
Basically, the logic is:
A equação exata.
O modelo exato.
So, I have removed as many words as possible.
The other way would be to only accept valid words, such as “equações”, “modelos”, etc. but I will miss most of them.
Unless you can create a list of these words to use with “exato”, but it must give too much work.