Check needed.

meli li ante e ma ali.
verb (the action occurring): ante (change)
subject (the one which does the action, i.e. who changes): meli (woman)
direct object (the thing which suffers the action, i.e. what is changed): ma ali (the entire world, the world, all lands...).

Note that this denotes, indeed, an action (not an affirmation about what the woman is), because we have "e", the particle before the direct object, and a direct object requires an action before it. This could be an affirmation about what the "meli" is only if there were not a direct object after "ante", like in these sentences: "meli li ante" (the woman is different), "meli li ante lon/tawa ma ali." (the woman is different in/for all lands = the woman is alien.)

This is not a problem of toki pona. Words in toki pona don't have fixed grammatical class, they can take different roles in a sentence and we can almost always predict how they translate into other languages. Just like "moku" means "eat", but in a nominal role it means "food", "ante" means "different", but in verbal role it means "change".

(please note that all my understandings about your comments are from google translation, because I know nothing about German, sorry)