It should certainly be reported to the sphinx tracker where the right people to make the decision for sphinx itself will see it.  Then if the decision is that type matters, python can decide how we want to handle that fact.  Since the core of sphinx does not care about type, I suspect this will be viewed as a bug in InterSphinx, but I could well be wrong.

Note that not using :func: does change the generated text.  With :func: you get () after the name, with :class: you don't.  So changing :func: to :class: for these is a decision that would need some discussion.

Also note that I'm guessing that there will be people who will object to expanding the description of the sequence types into full class/method docs.  So this, too, is a change that needs to be discussed with a wider audience.  I think I'm +0 on it myself; it makes the docs less concise and leads to redundant text, but it also make it easier to look up the method set of individual sequence types.