Portuguese to English Law/Patents Law (general)

This is a sentence from the Portuguese Civil Code (article 236), which reads as follows:

“A declaração negocial vale com o sentido que um declaratário normal, colocado na posição do real declaratário, possa deduzir do comportamento do declarante, salvo se este não puder razoavelmente contar com ele.”

I am struggling with the meaning of the last part of the sentence, “salvo se este não puder razoavelmente contar com ele”, mainly with regard to what “este” and “ele” specifically refer to.

Any explanations, in English or Portuguese, would be much appreciated. Thanks in advance.