Casuism and Rules in the Gemara

Hello Rabbi,
In the Gemara in Berakhot, page 12, it is written as follows: Tab Shema: Shacharit, start with Yotzer Or and end with Maariv Arabim – it did not come out, start with Maariv Arabim and end with Yotzer Or – it came out; Aravi, start with Maariv Arabim and end with Yotzer Or – it did not come out, start with Yotzer Or and end with Maariv Arabim – it came out; the general rule of the matter is: everything follows the sign… The general rule of the matter is for the Atui May – not for the Atui Ha Damran? – no, for the Atui Nehma and Tamari.
This means that if it were not written “in general,” we could not have understood Nehemiah and Tamar, and then in fact the Mishnah would only refer to the particular case of an error in the blessings of Kash and not in the other blessings. On the face of it, this contradicts your perception that the Mishnah came to convey a general principle through examples. Because, if this were the case, even without the phrase “in general,” we could learn that there is a hidden rule here that also applies to Nehemiah and Tamar. How can the contradiction be resolved, in your opinion?