you can say "interactions between other tribes", but "X interacted between other tribes" is wrong. (note that this part of the sentences follows tribes who interacted...)
by the same token, you can't use "X interacted among other tribes", either.

(d) and (e) contain a COMMA + -ING modifier that is used incorrectly.

a COMMA + -ING modifier is an adverbial modifier that modifies the entire clause to which it's attached, and is attributed to the subject of that clause.
in this context, you only want to modify the preceding noun ("tribes"), so COMMA + -ING is inappropriate.

2 idiom errors in (b):
* "interact" MUST be paired with "with". "interact between" and "interact among" are unidiomatic.
* "among each other" is unidiomatic (as is "between each other"); you should write "among themselves" or "between themselves". but, again, this doesn't work with "interact" anyway, so the issue is moot here.

The Kwakiutl recognized one social unit larger than the tribe--the confederacy, which was a cluster of loosely knit, informally related neighboring tribes.
K认识到一个比部落更大的社会单位--C，C是由松散连接、非正式相关的邻里部族组成的集群。knit是动词被动式，和related一起修饰tribes。
recognize，认出，承认，意识到，认为；a cluster of sth，一群

m

interact with one another表示另一个，each other表示互相
但interact among each other就不对了

名词和动词区别
interactions between other tribes✅
interacted between other tribes❌
interacted among other tribes❌
interacted with other tribes✅

each blames one another. 


one another一般用于“多于两者”的情况，即，例如一共有三个人，我们可以说：
这句话的意思是，每一个人责备三者中的一个。

each blames the other.


如果一共只有两个人，则我们会用：one another。
the other表示“另一个”。总数两个的情况下使用。

没有给tribes的范围，one another表示另一个，each other表示互相

两个中的“另一个”是“the other”
不定数目中的“另一个”是“another”

interactions between other tribes✅
interacted between other tribes❌
interacted among other tribes❌
interacted with other tribes✅

你这个tribe不是在、那里面的tribe而是另一个个体