In some cases, it is not so much the treatment of the animals on set in the studio that has activists worried;
it is the off-set training and living conditions that are raising concerns.
强调的内容应该是“not the treatment of the animals on set in the studio”，so much 是worried的修饰词，不应该放在worried的后面吗？
In some cases, it is not so much the treatment of the animals on set in the studio that has activists worried;
it is the off-set training and living conditions that are raising concerns.
两句话都是强调句。前句是不是定强调，后句是一定强调。平常，一定强调用居多。
前句 so much 与 not 连用，旨在表达一种否定上的语气。它与 worried 毫无干系。句子如此理解：
“与其说是如此” （否定了第一句，“与其说”也是一种否定格式），“倒不如说是那样“（第二句）。
so much 不需要也可，直接按否定翻译。
【注】表示择比，not so much 未必非要跟 as 连用，后面可以是分句（网友的句子），也可以用其他连词，如：
A good birth depends not so much on who you are, but where you are and how much you know.
好的出身与其说是取决于你的身份，还不如说是取决于你的生活环境和常识水平。
《柯林斯高阶英汉双解学习词典》
