Last week I wrote “てForm + います” expresses an action being undertaken and that in English the same thing can be described by using “be + ing”. It is true but it is not always true.
ジョンさんはすわっていますcan be translated as “John is sitting down” as I wrote last week but it does not mean that the action of “sitting down” is being undertaken. The action of “sitting down” is something that is over in a second, so in this case すわっています describes the continual state as a result of an action that has been completed. Oh, this sounds too technical… I don’t like that but …
When you go to a hospital with a broken bone, the doctor will say:
骨（ほね）が折（お）れています, although its English translation is “the bone is broken,” NOT “the bone is breaking.”
Similar examples are:
木（き）が枯（か）れています= the tree has died.
ベランダが濡（ぬ）れています= the veranda is wet.
Probably, I should write a bit more about these verbs but I will save it for later.
By the way, 骨が折れる is a set expression in Japanese to mean “to have a lot of trouble” and/or “it is hard work to ～”.
(= It is so much work to explain grammar.)