You are right, I suggested deleting too much. The first half of the sentence is needed to define 'type methods', which is used several more times and is the title of the next section. We need to keep "These C functions are called “type methods”." In the context of the preceding sentence and later usages, I think this is enough.

The second half of the sentence is intended to refine the definition by contrast, but it fails to do so since we cannot agree on what the contrast is. Since none of the interpretations make complete sense and since 'object methods' is not used again, making its definition irrelevant, I suggest deleting this part: "to distinguish them from things like [].append (which we call “object methods”).".