Mandarin is a spoken language. The characters are "Simplified Chinese" in this case. The characters will sound different read in different languages.

e.g. the two Traditional Chinese characters 東京 translate roughly to "Eastern Capital" and are read dōngjīng, while they are also valid Japanese Kanji where they have the same meaning and are read as Tokyo. (Yes, the name of the capital of Japan.) Interestingly, Běijīng and Nánjīng similarly mean "northern" and "southern" capital respectively.

There was once an Eastern Capital in China which is also named as Kaifeng, the capital of the Northen Song Dynasty. It is to east of Chang'an, which is now Xi'an, and the capital of most of earlier dynasties.

In Chinese culture, your male line ancestry matter more. Your mother's family is considered auxiliary ('外家'), thus only your father's brother's children are considered in the same family, and these cousins are labeled “堂”, all the other cousins are labeled "表”, and "姐" means older sister.

Is this why it is a mother's sibling of any gender, but only a father's sister?

That's my understanding, a difference is made between paternal lineages (through the father's brothers) and maternal (either father's sister or any sibling of the mother).

Possibly denoting similar v different family names?